Systems and methods for signaling general constraint information in video coding

ABSTRACT

A device may be configured to general constraint information according to one or more of the techniques described herein.

TECHNICAL FIELD

This disclosure relates to video coding and more particularly totechniques for signaling general constraint information for coded video.

BACKGROUND

Digital video capabilities can be incorporated into a wide range ofdevices, including digital televisions, laptop or desktop computers,tablet computers, digital recording devices, digital media players,video gaming devices, cellular telephones, including so-calledsmartphones, medical imaging devices, and the like. Digital video may becoded according to a video coding standard. Video coding standardsdefine the format of a compliant bitstream encapsulating coded videodata. A compliant bitstream is a data structure that may be received anddecoded by a video decoding device to generate reconstructed video data.Video coding standards may incorporate video compression techniques.Examples of video coding standards include ISO/IEC MPEG-4 Visual andITU-T H.264 (also known as ISO/IEC MPEG-4 AVC) and High-Efficiency VideoCoding (HEVC). HEVC is described in High Efficiency Video Coding (HEVC),Rec. ITU-T H.265, December 2016, which is incorporated by reference, andreferred to herein as ITU-T H.265. Extensions and improvements for ITU-TH.265 are currently being considered for the development of nextgeneration video coding standards. For example, the ITU-T Video CodingExperts Group (VCEG) and ISO/IEC (Moving Picture Experts Group (MPEG)(collectively referred to as the Joint Video Exploration Team (JVET))are working to standardized video coding technology with a compressioncapability that significantly exceeds that of the current HEVC standard.The Joint Exploration Model 7 (JEM 7), Algorithm Description of JointExploration Test Model 7 (JEM 7), ISO/IEC JTCUSC29/WG11 Document:JVET-G1001, July 2017, Torino, IT, which is incorporated by referenceherein, describes the coding features that were under coordinated testmodel study by the JVET as potentially enhancing video coding technologybeyond the capabilities of ITU-T H.265. It should be noted that thecoding features of JEM 7 are implemented in JEM reference software. Asused herein, the term JEM may collectively refer to algorithms includedin JEM 7 and implementations of JEM reference software. Further, inresponse to a “Joint Call for Proposals on Video Compression withCapabilities beyond HEVC,” jointly issued by VCEG and MPEG, multipledescriptions of video coding tools were proposed by various groups atthe 10^(th) Meeting of ISO/IEC JTCUSC29/WG11 16-20 Apr. 2018, San Diego,Calif. From the multiple descriptions of video coding tools, a resultinginitial draft text of a video coding specification is described in“Versatile Video Coding (Draft 1),” 10th Meeting of ISO/IECJTC1/SC29/WG11 16-20 Apr. 2018, San Diego, Calif., documentJVET-J1001-v2, which is incorporated by reference herein, and referredto as JVET-J1001. The current development of a next generation videocoding standard by the VCEG and MPEG is referred to as the VersatileVideo Coding (VVC) project. “Versatile Video Coding (Draft 9),” 18thMeeting of ISO/IEC JTC1/SC29/WG11 15-24 Apr. 2020, Teleconference,document JVET-R2001-vA, which is incorporated by reference herein, andreferred to as JVET-R2001, represents the current iteration of the drafttext of a video coding specification corresponding to the VVC project.

Video compression techniques enable data requirements for storing andtransmitting video data to be reduced. Video compression techniques mayreduce data requirements by exploiting the inherent redundancies in avideo sequence. Video compression techniques may sub-divide a videosequence into successively smaller portions (i.e., groups of pictureswithin a video sequence, a picture within a group of pictures, regionswithin a picture, sub-regions within regions, etc.). Intra predictioncoding techniques (e.g., spatial prediction techniques within a picture)and inter prediction techniques (i.e., inter-picture techniques(temporal)) may be used to generate difference values between a unit ofvideo data to be coded and a reference unit of video data. Thedifference values may be referred to as residual data. Residual data maybe coded as quantized transform coefficients. Syntax elements may relateresidual data and a reference coding unit (e.g., intra-prediction modeindices, and motion information). Residual data and syntax elements maybe entropy coded. Entropy encoded residual data and syntax elements maybe included in data structures forming a compliant bitstream.

SUMMARY OF INVENTION

A method of decoding video data, the method comprising:

receiving a profile level tier syntax structure providing levelinformation and, optionally, profile, tier, sub-profile, and generalconstraints information;

parsing a first syntax element indicating a level to which a videosequence conforms, and that is aligned as a second byte of the profilelevel tier syntax structure;

parsing a second syntax element specifying whether general constraintsinformation syntax elements are present in the profile level tier syntaxstructure; and

parsing a third syntax element, specifying whether a constraint isimposed, by using a value of the second syntax element.

A device comprising one or more processors configured to: receive aprofile level tier syntax structure providing level information and,optionally, profile, tier, sub-profile, and general constraintsinformation;

parse a first syntax element indicating a level to which a videosequence conforms, and that is aligned as a second byte of the profilelevel tier syntax structure;

parse a second syntax element specifying whether general constraintsinformation syntax elements are present in the profile level tier syntaxstructure; and

parse a third syntax element, specifying whether a constraint isimposed, by using a value of the second syntax element.

A method of encoding mage data, the method comprising:

signaling a profile level tier syntax structure providing levelinformation and, optionally, profile, tier, sub-profile, and generalconstraints information, wherein the profile level tier syntax structureincludes a first syntax element indicating a level to which a videosequence conforms, and that is aligned as a second byte of the profilelevel tier structure, the general constraints information includes (i) asecond syntax element specifying whether general constraints informationsyntax elements are present in the profile level tier syntax structureand (ii) a third syntax element, specifying whether a constraint isimposed, by using a value of the second syntax element.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an example of a system that maybe configured to encode and decode video data according to one or moretechniques of this disclosure.

FIG. 2 is a conceptual diagram illustrating coded video data andcorresponding data structures according to one or more techniques ofthis disclosure.

FIG. 3 is a conceptual diagram illustrating a data structureencapsulating coded video data and corresponding metadata according toone or more techniques of this disclosure.

FIG. 4 is a conceptual drawing illustrating an example of componentsthat may be included in an implementation of a system that may beconfigured to encode and decode video data according to one or moretechniques of this disclosure.

FIG. 5 is a block diagram illustrating an example of a video encoderthat may be configured to encode video data according to one or moretechniques of this disclosure.

FIG. 6 is a block diagram illustrating an example of a video decoderthat may be configured to decode video data according to one or moretechniques of this disclosure.

DETAILED DESCRIPTION

In general, this disclosure describes various techniques for codingvideo data. In particular, this disclosure describes techniques forsignaling general constraint information for coded video data. It shouldbe noted that although techniques of this disclosure are described withrespect to ITU-T H.264, ITU-T H.265, JEM, and JVET-R2001, the techniquesof this disclosure are generally applicable to video coding. Forexample, the coding techniques described herein may be incorporated intovideo coding systems, (including video coding systems based on futurevideo coding standards) including video block structures, intraprediction techniques, inter prediction techniques, transformtechniques, filtering techniques, and/or entropy coding techniques otherthan those included in ITU-T H.265, JEM, and JVET-R2001. Thus, referenceto ITU-T H.264, ITU-T H.265, JEM, and/or JVET-R2001 is for descriptivepurposes and should not be construed to limit the scope of thetechniques described herein. Further, it should be noted thatincorporation by reference of documents herein is for descriptivepurposes and should not be construed to limit or create ambiguity withrespect to terms used herein. For example, in the case where anincorporated reference provides a different definition of a term thananother incorporated reference and/or as the term is used herein, theterm should be interpreted in a manner that broadly includes eachrespective definition and/or in a manner that includes each of theparticular definitions in the alternative.

In one example, a method of signaling parameters for video datacomprises signaling a syntax element in a profile tier level syntaxstructure specifying whether a general constraint information syntaxstructure is present in the profile tier level syntax structure, andconditionally signaling a general constraint information syntaxstructure in the profile tier level syntax structure based on the valueof the syntax element.

In one example, a device comprises one or more processors configured tosignal a syntax element in a profile tier level syntax structurespecifying whether a general constraint information syntax structure ispresent in the profile tier level syntax structure, and conditionallysignal a general constraint information syntax structure in the profiletier level syntax structure based on the value of the syntax element.

In one example, a non-transitory computer-readable storage mediumcomprises instructions stored thereon that, when executed, cause one ormore processors of a device to signal a syntax element in a profile tierlevel syntax structure specifying whether a general constraintinformation syntax structure is present in the profile tier level syntaxstructure, and conditionally signal a general constraint informationsyntax structure in the profile tier level syntax structure based on thevalue of the syntax element.

In one example, an apparatus comprises means for signaling a syntaxelement in a profile tier level syntax structure specifying whether ageneral constraint information syntax structure is present in theprofile tier level syntax structure, and means for conditionallysignaling a general constraint information syntax structure in theprofile tier level syntax structure based on the value of the syntaxelement.

In one example, a method of decoding video data comprises parsing asyntax element in a profile tier level syntax structure specifyingwhether a general constraint information syntax structure is present inthe profile tier level syntax structure, and conditionally parsing ageneral constraint information syntax structure in the profile tierlevel syntax structure based on the value of the syntax element.

In one example, a device comprises one or more processors configured toparse a syntax element in a profile tier level syntax structurespecifying whether a general constraint information syntax structure ispresent in the profile tier level syntax structure, and conditionallyparse a general constraint information syntax structure in the profiletier level syntax structure based on the value of the syntax element.

In one example, a non-transitory computer-readable storage mediumcomprises instructions stored thereon that, when executed, cause one ormore processors of a device to parse a syntax element in a profile tierlevel syntax structure specifying whether a general constraintinformation syntax structure is present in the profile tier level syntaxstructure, and conditionally parse a general constraint informationsyntax structure in the profile tier level syntax structure based on thevalue of the syntax element.

In one example, an apparatus comprises means for parsing a syntaxelement in a profile tier level syntax structure specifying whether ageneral constraint information syntax structure is present in theprofile tier level syntax structure, and means for conditionally parsinga general constraint information syntax structure in the profile tierlevel syntax structure based on the value of the syntax element.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

Video content includes video sequences comprised of a series of frames(or pictures). A series of frames may also be referred to as a group ofpictures (GOP). Each video frame or picture may divided into one or moreregions. Regions may be defined according to a base unit (e.g., a videoblock) and sets of rules defining a region. For example, a rule defininga region may be that a region must be an integer number of video blocksarranged in a rectangle. Further, video blocks in a region may beordered according to a scan pattern (e.g., a raster scan). As usedherein, the term video block may generally refer to an area of a pictureor may more specifically refer to the largest array of sample valuesthat may be predictively coded, sub-divisions thereof, and/orcorresponding structures. Further, the term current video block mayrefer to an area of a picture being encoded or decoded. A video blockmay be defined as an array of sample values. It should be noted that insome cases pixel values may be described as including sample values forrespective components of video data, which may also be referred to ascolor components, (e.g., luma (Y) and chroma (Cb and Cr) components orred, green, and blue components). It should be noted that in some cases,the terms pixel value and sample value are used interchangeably.Further, in some cases, a pixel or sample may be referred to as a pel. Avideo sampling format, which may also be referred to as a chroma format,may define the number of chroma samples included in a video block withrespect to the number of luma samples included in a video block. Forexample, for the 4:2:0 sampling format, the sampling rate for the lumacomponent is twice that of the chroma components for both the horizontaland vertical directions.

A video encoder may perform predictive encoding on video blocks andsub-divisions thereof. Video blocks and sub-divisions thereof may bereferred to as nodes. ITU-T H.264 specifies a macroblock including 16×16luma samples. That is, in ITU-T H.264, a picture is segmented intomacroblocks. ITU-T H.265 specifies an analogous Coding Tree Unit (CTU)structure (which may be referred to as a largest coding unit (LCU)). InITU-T H.265, pictures are segmented into CTUs. In ITU-T H.265, for apicture, a CTU size may be set as including 16×16, 32×32, or 64×64 lumasamples. In ITU-T H.265, a CTU is composed of respective Coding TreeBlocks (CTB) for each component of video data (e.g., luma (Y) and chroma(Cb and Cr). It should be noted that video having one luma component andthe two corresponding chroma components may be described as having twochannels, i.e., a luma channel and a chroma channel. Further, in ITU-TH.265, a CTU may be partitioned according to a quadtree (QT)partitioning structure, which results in the CTBs of the CTU beingpartitioned into Coding Blocks (CB). That is, in ITU-T H.265, a CTU maybe partitioned into quadtree leaf nodes. According to ITU-T H.265, oneluma CB together with two corresponding chroma CBs and associated syntaxelements are referred to as a coding unit (CU). In ITU-T H.265, aminimum allowed size of a CB may be signaled. In ITU-T H.265, thesmallest minimum allowed size of a luma CB is 8×8 luma samples. In ITU-TH.265, the decision to code a picture area using intra prediction orinter prediction is made at the CU level.

In ITU-T H.265, a CU is associated with a prediction unit structurehaving its root at the CU. In ITU-T H.265, prediction unit structuresallow luma and chroma CBs to be split for purposes of generatingcorresponding reference samples. That is, in ITU-T H.265, luma andchroma CBs may be split into respective luma and chroma predictionblocks (PBs), where a PB includes a block of sample values for which thesame prediction is applied. In ITU-T H.265, a CB may be partitioned into1, 2, or 4 PBs. ITU-T H.265 supports PB sizes from 64×64 samples down to4×4 samples. In ITU-T H.265, square PBs are supported for intraprediction, where a CB may form the PB or the CB may be split into foursquare PBs. In ITU-T H.265, in addition to the square PBs, rectangularPBs are supported for inter prediction, where a CB may by halvedvertically or horizontally to form PBs. Further, it should be noted thatin ITU-T H.265, for inter prediction, four asymmetric PB partitions aresupported, where the CB is partitioned into two PBs at one quarter ofthe height (at the top or the bottom) or width (at the left or theright) of the CB. Intra prediction data (e.g., intra prediction modesyntax elements) or inter prediction data (e.g., motion data syntaxelements) corresponding to a PB is used to produce reference and/orpredicted sample values for the PB.

JEM specifies a CTU having a maximum size of 256×256 luma samples. JEMspecifies a quadtree plus binary tree (QTBT) block structure. In JEM,the QTBT structure enables quadtree leaf nodes to be further partitionedby a binary tree (BT) structure. That is, in JEM, the binary treestructure enables quadtree leaf nodes to be recursively dividedvertically or horizontally. In JVET-R2001, CTUs are partitionedaccording a quadtree plus multi-type tree (QTMT or QT+MTT) structure.The QTMT in JVET-R2001 is similar to the QTBT in JEM. However, inJVET-R2001, in addition to indicating binary splits, the multi-type treemay indicate so-called ternary (or triple tree (TT)) splits. A ternarysplit divides a block vertically or horizontally into three blocks. Inthe case of a vertical TT split, a block is divided at one quarter ofits width from the left edge and at one quarter its width from the rightedge and in the case of a horizontal TT split a block is at one quarterof its height from the top edge and at one quarter of its height fromthe bottom edge.

As described above, each video frame or picture may be divided into oneor more regions. For example, according to ITU-T H.265, each video frameor picture may be partitioned to include one or more slices and furtherpartitioned to include one or more tiles, where each slice includes asequence of CTUs (e.g., in raster scan order) and where a tile is asequence of CTUs corresponding to a rectangular area of a picture. Itshould be noted that a slice, in ITU-T H.265, is a sequence of one ormore slice segments starting with an independent slice segment andcontaining all subsequent dependent slice segments (if any) that precedethe next independent slice segment (if any). A slice segment, like aslice, is a sequence of CTUs. Thus, in some cases, the terms slice andslice segment may be used interchangeably to indicate a sequence of CTUsarranged in a raster scan order. Further, it should be noted that inITU-T H.265, a tile may consist of CTUs contained in more than one sliceand a slice may consist of CTUs contained in more than one tile.However, ITU-T H.265 provides that one or both of the followingconditions shall be fulfilled: (1) All CTUs in a slice belong to thesame tile; and (2) All CTUs in a tile belong to the same slice.

With respect to JVET-R2001, slices are required to consist of an integernumber of complete tiles or an integer number of consecutive completeCTU rows within a tile, instead of only being required to consist of aninteger number of CTUs. It should be noted that in JVET-R2001, the slicedesign does not include slice segments (i.e., no independent/dependentslice segments). Thus, in JVET-R2001, a picture may include a singletile, where the single tile is contained within a single slice or apicture may include multiple tiles where the multiple tiles (or CTU rowsthereof) may be contained within one or more slices. In JVET-R2001, thepartitioning of a picture into tiles is specified by specifyingrespective heights for tile rows and respective widths for tile columns.Thus, in JVET-R2001 a tile is a rectangular region of CTUs within aparticular tile row and a particular tile column position. Further, itshould be noted that JVET-R2001 provides where a picture may bepartitioned into subpictures, where a subpicture is a rectangular regionof a CTUs within a picture. The top-left CTU of a subpicture may belocated at any CTU position within a picture with subpictures beingconstrained to include one or more slices Thus, unlike a tile, asubpicture is not necessarily limited to a particular row and columnposition. It should be noted that subpictures may be useful forencapsulating regions of interest within a picture and a sub-bitstreamextraction process may be used to only decode and display a particularregion of interest. That is, as described in further detail below, abitstream of coded video data includes a sequence of network abstractionlayer (NAL) units, where a NAL unit encapsulates coded video data,(i.e., video data corresponding to a slice of picture) or a NAL unitencapsulates metadata used for decoding video data (e.g., a parameterset) and a sub-bitstream extraction process forms a new bitstream byremoving one or more NAL units from a bitstream.

FIG. 2 is a conceptual diagram illustrating an example of a picturewithin a group of pictures partitioned according to tiles, slices, andsubpictures. It should be noted that the techniques described herein maybe applicable to tiles, slices, subpictures, sub-divisions thereofand/or equivalent structures thereto. That is, the techniques describedherein may be generally applicable regardless of how a picture ispartitioned into regions. For example, in some cases, the techniquesdescribed herein may be applicable in cases where a tile may bepartitioned into so-called bricks, where a brick is a rectangular regionof CTU rows within a particular tile. Further, for example, in somecases, the techniques described herein may be applicable in cases whereone or more tiles may be included in so-called tile groups, where a tilegroup includes an integer number of adjacent tiles. In the exampleillustrated in FIG. 2 , Pic₃ is illustrated as including 16 tiles (i.e.,Tile₀ to Tile₁₅) and three slices (i.e., Slice₀ to Slice₂). In theexample illustrated in FIG. 2 , Slice₀ includes four tiles (i.e., Tile₀to Tile₃), Slice₁ includes eight tiles (i.e., Tile₄ to Tile₁₁), andSlice₂ includes four tiles (i.e., Tile₁₂ to Tile₁₅). Further, asillustrated in the example of FIG. 2 , Pic₃ is illustrated as includingtwo subpictures (i.e., Subpicture₀ and Subpicture₁), where Subpicture₀includes Slice₀ and Slice₁ and where Subpicture₁ includes Slice₂. Asdescribed above, subpictures may be useful for encapsulating regions ofinterest within a picture and a sub-bitstream extraction process may beused in order to selectively decode (and display) a region interest. Forexample, referring to FIG. 2 , Subpicture₀ may corresponding to anaction portion of a sporting event presentation (e.g., a view of thefield) and Subpicture₁ may corresponding to a scrolling banner displayedduring the sporting event presentation. By using organizing a pictureinto subpictures in this manner, a viewer may be able to disable thedisplay of the scrolling banner. That is, through a sub-bitstreamextraction process Slice₂ NAL unit may be removed from a bitstream (andthus not decoded and/or displayed) and Slice® NAL unit and Slice₁ NALunit may be decoded and displayed. The encapsulation of slices of apicture into respective NAL unit data structures and sub-bitstreamextraction are described in further detail below.

For intra prediction coding, an intra prediction mode may specify thelocation of reference samples within a picture. In ITU-T H.265, definedpossible intra prediction modes include a planar (i.e., surface fitting)prediction mode, a DC (i.e., flat overall averaging) prediction mode,and 33 angular prediction modes (predMode: 2-34). In JEM, definedpossible intra-prediction modes include a planar prediction mode, a DCprediction mode, and 65 angular prediction modes. It should be notedthat planar and DC prediction modes may be referred to asnon-directional prediction modes and that angular prediction modes maybe referred to as directional prediction modes. It should be noted thatthe techniques described herein may be generally applicable regardlessof the number of defined possible prediction modes.

For inter prediction coding, a reference picture is determined and amotion vector (MV) identifies samples in the reference picture that areused to generate a prediction for a current video block. For example, acurrent video block may be predicted using reference sample valueslocated in one or more previously coded picture(s) and a motion vectoris used to indicate the location of the reference block relative to thecurrent video block. A motion vector may describe, for example, ahorizontal displacement component of the motion vector (i.e., MV_(x)), avertical displacement component of the motion vector (i.e., MV_(y)), anda resolution for the motion vector (e.g., one-quarter pixel precision,one-half pixel precision, one-pixel precision, two-pixel precision,four-pixel precision). Previously decoded pictures, which may includepictures output before or after a current picture, may be organized intoone or more to reference pictures lists and identified using a referencepicture index value. Further, in inter prediction coding, uni-predictionrefers to generating a prediction using sample values from a singlereference picture and bi-prediction refers to generating a predictionusing respective sample values from two reference pictures. That is, inuni-prediction, a single reference picture and corresponding motionvector are used to generate a prediction for a current video block andin bi-prediction, a first reference picture and corresponding firstmotion vector and a second reference picture and corresponding secondmotion vector are used to generate a prediction for a current videoblock. In bi-prediction, respective sample values are combined (e.g.,added, rounded, and clipped, or averaged according to weights) togenerate a prediction. Pictures and regions thereof may be classifiedbased on which types of prediction modes may be utilized for encodingvideo blocks thereof. That is, for regions having a B type (e.g., a Bslice), bi-prediction, uni-prediction, and intra prediction modes may beutilized, for regions having a P type (e.g., a P slice), uni-prediction,and intra prediction modes may be utilized, and for regions having an Itype (e.g., an I slice), only intra prediction modes may be utilized. Asdescribed above, reference pictures are identified through referenceindices. For example, for a P slice, there may be a single referencepicture list, RefPicList0 and for a B slice, there may be a secondindependent reference picture list, RefPicList1, in addition toRefPicList0. It should be noted that for uni-prediction in a B slice,one of RefPicList0 or RefPicList1 may be used to generate a prediction.Further, it should be noted that during the decoding process, at theonset of decoding a picture, reference picture list(s) are generatedfrom previously decoded pictures stored in a decoded picture buffer(DPB).

Further, a coding standard may support various modes of motion vectorprediction. Motion vector prediction enables the value of a motionvector for a current video block to be derived based on another motionvector. For example, a set of candidate blocks having associated motioninformation may be derived from spatial neighboring blocks and temporalneighboring blocks to the current video block. Further, generated (ordefault) motion information may be used for motion vector prediction.Examples of motion vector prediction include advanced motion vectorprediction (AMVP), temporal motion vector prediction (TMVP), so-called“merge” mode, and “skip” and “direct” motion inference. Further, otherexamples of motion vector prediction include advanced temporal motionvector prediction (ATMVP) and Spatial-temporal motion vector prediction(STMVP). For motion vector prediction, both a video encoder and videodecoder perform the same process to derive a set of candidates. Thus,for a current video block, the same set of candidates is generatedduring encoding and decoding.

As described above, for inter prediction coding, reference samples in apreviously coded picture are used for coding video blocks in a currentpicture. Previously coded pictures which are available for use asreference when coding a current picture are referred as referencepictures. It should be noted that the decoding order does not necessarycorrespond with the picture output order, i.e., the temporal order ofpictures in a video sequence. In ITU-T H.265, when a picture is decodedit is stored to a decoded picture buffer (DPB) (which may be referred toas frame buffer, a reference buffer, a reference picture buffer, or thelike). In ITU-T H.265, pictures stored to the DPB are removed from theDPB when they been output and are no longer needed for coding subsequentpictures. In ITU-T H.265, a determination of whether pictures should beremoved from the DPB is invoked once per picture, after decoding a sliceheader, i.e., at the onset of decoding a picture. For example, referringto FIG. 2 , Pic₂ is illustrated as referencing Pic₁. Similarly, Pic₃ isillustrated as referencing Pic₀. With respect to FIG. 2 , assuming thepicture number corresponds to the decoding order, the DPB would bepopulated as follows: after decoding Pic₀, the DPB would include {Pic₀};at the onset of decoding Pic_(k) the DPB would include {Pic₀}; afterdecoding Pic_(k) the DPB would include {Pic₀, Pic₁}; at the onset ofdecoding Pic₂, the DPB would include {Pic₀, Pic₁}. Pic₂ would then bedecoded with reference to Pic₁ and after decoding Pic₂, the DPB wouldinclude {Pic₀, Pic₁, Pic₂}. At the onset of decoding Pic₃, pictures Pic₀and Pic₁ would be marked for removal from the DPB, as they are notneeded for decoding Pic₃ (or any subsequent pictures, not shown) andassuming Pic₁ and Pic₂ have been output, the DPB would be updated toinclude {Pic₀}. Pic₃ would then be decoded by referencing Pic₀. Theprocess of marking pictures for removal from a DPB may be referred to asreference picture set (RPS) management.

As described above, intra prediction data or inter prediction data isused to produce reference sample values for a block of sample values.The difference between sample values included in a current PB, oranother type of picture area structure, and associated reference samples(e.g., those generated using a prediction) may be referred to asresidual data. Residual data may include respective arrays of differencevalues corresponding to each component of video data. Residual data maybe in the pixel domain. A transform, such as, a discrete cosinetransform (DCT), a discrete sine transform (DST), an integer transform,a wavelet transform, or a conceptually similar transform, may be appliedto an array of difference values to generate transform coefficients. Itshould be noted that in ITU-T H.265 and JVET-R2001, a CU is associatedwith a transform tree structure having its root at the CU level. Thetransform tree is partitioned into one or more transform units (TUs).That is, an array of difference values may be partitioned for purposesof generating transform coefficients (e.g., four 8×8 transforms may beapplied to a 16×16 array of residual values). For each component ofvideo data, such sub-divisions of difference values may be referred toas Transform Blocks (TBs). It should be noted that in some cases, a coretransform and subsequent secondary transforms may be applied (in thevideo encoder) to generate transform coefficients. For a video decoder,the order of transforms is reversed.

A quantization process may be performed on transform coefficients orresidual sample values directly (e.g., in the case, of palette codingquantization). Quantization approximates transform coefficients byamplitudes restricted to a set of specified values. Quantizationessentially scales transform coefficients in order to vary the amount ofdata required to represent a group of transform coefficients.Quantization may include division of transform coefficients (or valuesresulting from the addition of an offset value to transformcoefficients) by a quantization scaling factor and any associatedrounding functions (e.g., rounding to the nearest integer). Quantizedtransform coefficients may be referred to as coefficient level values.Inverse quantization (or “dequantization”) may include multiplication ofcoefficient level values by the quantization scaling factor, and anyreciprocal rounding or offset addition operations. It should be notedthat as used herein the term quantization process in some instances mayrefer to division by a scaling factor to generate level values andmultiplication by a scaling factor to recover transform coefficients insome instances. That is, a quantization process may refer toquantization in some cases and inverse quantization in some cases.Further, it should be noted that although in some of the examples belowquantization processes are described with respect to arithmeticoperations associated with decimal notation, such descriptions are forillustrative purposes and should not be construed as limiting. Forexample, the techniques described herein may be implemented in a deviceusing binary operations and the like. For example, multiplication anddivision operations described herein may be implemented using bitshifting operations and the like.

Quantized transform coefficients and syntax elements (e.g., syntaxelements indicating a coding structure for a video block) may be entropycoded according to an entropy coding technique. An entropy codingprocess includes coding values of syntax elements using lossless datacompression algorithms. Examples of entropy coding techniques includecontent adaptive variable length coding (CAVLC), context adaptive binaryarithmetic coding (CABAC), probability interval partitioning entropycoding (PIPE), and the like. Entropy encoded quantized transformcoefficients and corresponding entropy encoded syntax elements may forma compliant bitstream that can be used to reproduce video data at avideo decoder. An entropy coding process, for example, CABAC, mayinclude performing a binarization on syntax elements. Binarizationrefers to the process of converting a value of a syntax element into aseries of one or more bits. These bits may be referred to as “bins.”Binarization may include one or a combination of the following codingtechniques: fixed length coding, unary coding, truncated unary coding,truncated Rice coding, Golomb coding, k-th order exponential Golombcoding, and Golomb-Rice coding. For example, binarization may includerepresenting the integer value of 5 for a syntax element as 00000101using an 8-bit fixed length binarization technique or representing theinteger value of 5 as 11110 using a unary coding binarization technique.As used herein each of the terms fixed length coding, unary coding,truncated unary coding, truncated Rice coding, Golomb coding, k-th orderexponential Golomb coding, and Golomb-Rice coding may refer to generalimplementations of these techniques and/or more specific implementationsof these coding techniques. For example, a Golomb-Rice codingimplementation may be specifically defined according to a video codingstandard. In the example of CABAC, for a particular bin, a contextprovides a most probable state (MPS) value for the bin (i.e., an MPS fora bin is one of 0 or 1) and a probability value of the bin being the MPSor the least probably state (LPS). For example, a context may indicate,that the MPS of a bin is 0 and the probability of the bin being 1 is0.3. It should be noted that a context may be determined based on valuesof previously coded bins including bins in the current syntax elementand previously coded syntax elements. For example, values of syntaxelements associated with neighboring video blocks may be used todetermine a context for a current bin.

With respect to the equations used herein, the following arithmeticoperators may be used:

-   + Addition-   − Subtraction-   *Multiplication, including matrix multiplication-   x^(y) Exponentiation. Specifies x to the power of y. In other    contexts, such notation is used for superscripting not intended for    interpretation as exponentiation.-   / Integer division with truncation of the result toward zero. For    example, 7/4 and −7/−4 are truncated to 1 and −7/4 and 7/−4 are    truncated to −1.-   ÷ Used to denote division in mathematical equations where no    truncation or rounding is intended.

$\frac{x}{y}$Used to denote division in mathematical equations where no truncation orrounding is intended.

Further, the following mathematical functions may be used:

Log 2(x) the base-2 logarithm of x;

${{Min}( {x,y} )} = \{ {\begin{matrix}{x\ ;\ {{x <} = y}} \\{y\ ;\ {x > y}}\end{matrix};{{{Max}( {x,y} )} = \{ \begin{matrix}{x;{{x >} = y}} \\{y\ ;{x < y}}\end{matrix} }} $

Ceil(x) the smallest integer greater than or equal to x.

With respect to the example syntax used herein, the followingdefinitions of logical operators may be applied:

x && y Boolean logical “and” of x and y

x∥y Boolean logical “or” of x and y

! Boolean logical “not”

x ? y: z If x is TRUE or not equal to 0, evaluates to the value of y;otherwise, evaluates to the value of z.

Further, the following relational operators may be applied:

-   -   > Greater than    -   >= Greater than or equal to    -   < Less than    -   <= Less than or equal to    -   == Equal to    -   != Not equal to

Further, it should be noted that in the syntax descriptors used herein,the following descriptors may be applied:

-   -   b(8): byte having any pattern of bit string (8 bits). The        parsing process for this descriptor is specified by the return        value of the function read_bits(8).    -   f(n): fixed-pattern bit string using n bits written (from left        to right) with the left bit first. The parsing process for this        descriptor is specified by the return value of the function        read_bits(n).    -   se(v): signed integer 0-th order Exp-Golomb-coded syntax element        with the left bit first.    -   tb(v): truncated binary using up to maxVal bits with maxVal        defined in the semantics of the symtax element.    -   tu(v): truncated unary using up to maxVal bits with maxVal        defined in the semantics of the symtax element.    -   u(n): unsigned integer using n bits. When n is “v” in the syntax        table, the number of bits varies in a manner dependent on the        value of other syntax elements. The parsing process for this        descriptor is specified by the return value of the function        read_bits(n) interpreted as a binary representation of an        unsigned integer with most significant bit written first.    -   ue(v): unsigned integer 0-th order Exp-Golomb-coded syntax        element with the left bit first.

As described above, video content includes video sequences comprised ofa series of pictures and each picture may be divided into one or moreregions. In JVET-R2001, a coded representation of a picture comprisesVCL NAL units of a particular layer within an AU and contains all CTUsof the picture. For example, referring again to FIG. 2 , the codedrepresentation of Pica is encapsulated in three coded slice NAL units(i.e., Slice® NAL unit, Slice₁ NAL unit, and Slice₂ NAL unit). It shouldbe noted that the term video coding layer (VCL) NAL unit is used as acollective term for coded slice NAL units, i.e., VCL NAL is a collectiveterm which includes all types of slice NAL units. As described above,and in further detail below, a NAL unit may encapsulate metadata usedfor decoding video data. A NAL unit encapsulating metadata used fordecoding a video sequence is generally referred to as a non-VCL NALunit. Thus, in JVET-R2001, a NAL unit may be a VCL NAL unit or a non-VCLNAL unit. It should be noted that a VCL NAL unit includes slice headerdata, which provides information used for decoding the particular slice.Thus, in JVET-R2001, information used for decoding video data, which maybe referred to as metadata in some cases, is not limited to beingincluded in non-VCL NAL units. JVET-R2001 provides where a picture unit(PU) is a set of NAL units that are associated with each other accordingto a specified classification rule, are consecutive in decoding order,and contain exactly one coded picture and where an access unit (AU) is aset of PUs that belong to different layers and contain coded picturesassociated with the same time for output from the DPB. JVET-R2001further provides where a layer is a set of VCL NAL units that all have aparticular value of a layer identifier and the associated non-VCL NALunits. Further, in JVET-R2001, a PU consists of zero or one PH NALunits, one coded picture, which comprises of one or more VCL NAL units,and zero or more other non-VCL NAL units. Further, in JVET-R2001, acoded video sequence (CVS) is a sequence of AUs that consists, indecoding order, of a CVSS AU, followed by zero or more AUs that are notCVSS AUs, including all subsequent AUs up to but not including anysubsequent AU that is a CVSS AU, where a coded video sequence start(CVSS) AU is an AU in which there is a PU for each layer in the CVS andthe coded picture in each present picture unit is a coded layer videosequence start (CLVSS) picture. In JVET-R2001, a coded layer videosequence (CLVS) is a sequence of PUs within the same layer thatconsists, in decoding order, of a CLVSS PU, followed by zero or more PUsthat are not CLVSS PUs, including all subsequent PUs up to but notincluding any subsequent PU that is a CLVSS PU. This is, in JVET-R2001,a bitstream may be described as including a sequence of AUs forming oneor more CVSs.

Multi-layer video coding enables a video presentation to bedecoded/displayed as a presentation corresponding to a base layer ofvideo data and decoded/displayed one or more additional presentationscorresponding to enhancement layers of video data. For example, a baselayer may enable a video presentation having a basic level of quality(e.g., a High Definition rendering and/or a 30 Hz frame rate) to bepresented and an enhancement layer may enable a video presentationhaving an enhanced level of quality (e.g., an Ultra High Definitionrendering and/or a 60 Hz frame rate) to be presented. An enhancementlayer may be coded by referencing a base layer. That is, for example, apicture in an enhancement layer may be coded (e.g., using inter-layerprediction techniques) by referencing one or more pictures (includingscaled versions thereof) in a base layer. It should be noted that layersmay also be coded independent of each other. In this case, there may notbe inter-layer prediction between two layers. Each NAL unit may includean identifier indicating a layer of video data the NAL unit isassociated with. As described above, a sub-bitstream extraction processmay be used to only decode and display a particular region of interestof a picture. Further, a sub-bitstream extraction process may be used toonly decode and display a particular layer of video. Sub-bitstreamextraction may refer to a process where a device receiving a compliantor conforming bitstream forms a new compliant or conforming bitstream bydiscarding and/or modifying data in the received bitstream. For example,sub-bitstream extraction may be used to form a new compliant orconforming bitstream corresponding to a particular representation ofvideo (e.g., a high quality representation).

In JVET-R2001, each of a video sequence, a GOP, a picture, a slice, andCTU may be associated with metadata that describes video codingproperties and some types of metadata an encapsulated in non-VCL NALunits. JVET-R2001 defines parameters sets that may be used to describevideo data and/or video coding properties. In particular, JVET-R2001includes the following four types of parameter sets: video parameter set(VPS), sequence parameter set (SPS), picture parameter set (PPS), andadaption parameter set (APS), where a SPS applies to apply to zero ormore entire CVSs, a PPS applies to zero or more entire coded pictures, aAPS applies to zero or more slices, and a VPS may be optionallyreferenced by a SPS. A PPS applies to an individual coded picture thatrefers to it. In JVET-R2001, parameter sets may be encapsulated as anon-VCL NAL unit and/or may be signaled as a message. JVET-R2001 alsoincludes a picture header (PH) which is encapsulated as a non-VCL NALunit. In JVET-R2001, a picture header applies to all slices of a codedpicture. JVET-R2001 further enables decoding capability information(DCI) and supplemental enhancement information (SEI) messages to besignaled. In JVET-R2001, DCI and SEI messages assist in processesrelated to decoding, display or other purposes, however, DCI and SEImessages may not be required for constructing the luma or chroma samplesaccording to a decoding process. In JVET-R2001, DCI and SEI messages maybe signaled in a bitstream using non-VCL NAL units. Further, DCI and SEImessages may be conveyed by some mechanism other than by being presentin the bitstream (i.e., signaled out-of-band).

FIG. 3 illustrates an example of a bitstream including multiple CVSs,where a CVS includes AUs, and AUs include picture units. The exampleillustrated in FIG. 3 corresponds to an example of encapsulating theslice NAL units illustrated in the example of FIG. 2 in a bitstream. Inthe example illustrated in FIG. 3 , the corresponding picture unit forPic₃ includes the three VCL NAL coded slice NAL units, i.e., Slice₁ NALunit, Slices NAL unit, and Slice₂ NAL unit and two non-VCL NAL units,i.e., a PPS NAL Unit and a PH NAL unit. It should be noted that in FIG.3 , HEADER is a NAL unit header (i.e., not to be confused with a sliceheader). Further, it should be noted that in FIG. 3 , other non-VCL NALunits, which are not illustrated may be included in the CVSs, e.g., SPSNAL units, VPS NAL units, SEI message NAL units, etc. Further, it shouldbe noted that in other examples, a PPS NAL Unit used for decoding Pic₃may be included elsewhere in the bitstream, e.g., in the picture unitcorresponding to Pic₀ or may be provided by an external mechanism. Asdescribed in further detail below, in JVET-R2001, a PH syntax structuremay be present in the slice header of a VCL NAL unit or in a PH NAL unitof the current PU.

JVET-R2001 defines NAL unit header semantics that specify the type ofRaw Byte Sequence Payload (RBSP) data structure included in the NALunit. Table 1 illustrates the syntax of the NAL unit header provided inJVET-R2001.

TABLE 1 Descriptor nal_unit_header( ) { forbidden_zero_bit f(1)nuh_reserved_zero_bit u(1) nuh_layer_id u(6) nal_unit_type u(5)nuh_temporal_id_plus1 u(3) }

JVET-R2001 provides the following definitions for the respective syntaxelements illustrated in Table 1.

forbidden_zero_bit shall be equal to 0.

nuh_reserved_zero_bit shall be equal to ‘0’. The value 1 ofnuh_reserved_zero_bit may be specified in the future by ITU-T|ISO/IEC.Decoders shall ignore (i.e. remove from the bitstream and discard) NALunits with nuh_reserved_zero_bit equal to ‘1’.

nuh_layer_id specifies the identifier of the layer to which a VCL NALunit belongs or the identifier of a layer to which a non-VCL NAL unitapplies. The value of nuh_layer_id shall be in the range of 0 to 55,inclusive. Other values for nuh_layer_id are reserved for future use byITU-T|ISO/IEC.The value of nuh_layer_id shall be the same for all VCL NAL units of acoded picture. The value of nuh_layer_id of a coded picture or a PU isthe value of the nuh_layer_id of the VCL NAL units of the coded pictureor the PU.When nal_unit_type is equal to PH_NUT, EOS_NUT, or FD_NUT, nuh_layer_idshall be equal to the nuh_layer_id of associated VCL NAL unit.

NOTE—The value of nuh_layer_id of DCI, VPS, AUD, and EOB NAL units isnot constrained.

nuh_temporal_id_plus1 minus 1 specifies a temporal identifier for theNAL unit.

The value of nuh_temporal_id_plus1 shall not be equal to 0.

The variable TemporalId is derived as follows:

-   -   TemporalId=nuh_temporal_id_plus1−1        When nal_unit_type is in the range of IDR_W_RADL to RSV_IRAP_12,        inclusive, TemporalId shall be equal to 0.        When nal_unit_type is equal to STSA_NUT and        vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ] is        equal to 1, TemporalId shall not be equal to 0.        The value of TemporalId shall be the same for all VCL NAL units        of an AU. The value of TemporalId of a coded picture, a PU, or        an AU is the value of the TemporalId of the VCL NAL units of the        coded picture, PU, or AU. The value of TemporalId of a sublayer        representation is the greatest value of TemporalId of all VCL        NAL units in the sublayer representation.        The value of TemporalId for non-VCL NAL units is constrained as        follows:    -   If nal_unit_type is equal to DCI_NUT, VPS_NUT, or SPS_NUT,        TemporalId shall be equal to 0 and the TemporalId of the AU        containing the NAL unit shall be equal to 0.    -   Otherwise, if nal_unit_type is equal to PH_NUT, TemporalId shall        be equal to the TemporalId of the PU containing the NAL unit.    -   Otherwise, if nal_unit_type is equal to EOS_NUT or EOB_NUT,        TemporalId shall be equal to 0.    -   Otherwise, if nal_unit_type is equal to AUD_NUT, FD_NUT,        PREFIX_SEI_NUT, or SUFFIX_SEI_NUT, TemporalId shall be equal to        the TemporalId of the AU containing the NAL unit.    -   Otherwise, when nal_unit_type is equal to PPS_NUT,        PREFIX_APS_NUT, or SUFFIX_APS_NUT, TemporalId shall be greater        than or equal to the TemporalId of the PU containing the NAL        unit.        NOTE—When the NAL unit is a non-VCL NAL unit, the value of        TemporalId is equal to the minimum value of the TemporalId        values of all AUs to which the non-VCL NAL unit applies. When        nal_unit_type is equal to PPS_NUT, PREFIX_APS_NUT, or        SUFFIX_APS_NUT, TemporalId may be greater than or equal to the        TemporalId of the containing AU, as all PPSs and APSs may be        included in the beginning of the bitstream (e.g., when they are        transported out-of-band, and the receiver places them at the        beginning of the bitstream), wherein the first coded picture has        TemporalId equal to 0.        nal_unit_type specifies the NAL unit type, i.e., the type of        RBSP data structure contained in the NAL unit as specified in        Table 2.        The value of nal_unit_type shall be the same for all pictures of        a CVSS AU.        NAL units that have nal_unit_type in the range of UNSPEC28 . . .        UNSPEC31, inclusive, for which semantics are not specified,        shall not affect the decoding process specified in this        Specification.

NOTE—NAL unit types in the range of UNSPEC28 . . . UNSPEC31 may be usedas determined by the application. No decoding process for these valuesof nal_unit_type is specified in this Specification. Since differentapplications might use these NAL unit types for different purposes,particular care must be exercised in the design of encoders thatgenerate NAL units with these nal_unit_type values, and in the design ofdecoders that interpret the content of NAL units with thesenal_unit_type values. This Specification does not define any managementfor these values. These nal_unit_type values might only be suitable foruse in contexts in which “collisions” of usage (i.e., differentdefinitions of the meaning of the NAL unit content for the samenal_unit_type value) are unimportant, or not possible, or aremanaged—e.g., defined or managed in the controlling application ortransport specification, or by controlling the environment in whichbitstreams are distributed.

For purposes other than determining the amount of data in the decodingunits of the bitstream, decoders shall ignore (remove from the bitstreamand discard) the contents of all NAL units that use reserved values ofnal_unit_type.

NOTE—This requirement allows future definition of compatible extensionsto this Specification.

TABLE 2 Name of NAL unit nal_unit_type nal_unit_type Content of NAL unitand RBSP syntax structure type class 0 TRAIL_NUT Coded slice of atrailing picture or subpicture* VCL slice_layer_rbsp( ) 1 STSA_NUT Codedslice of an STSA picture or subpicture* VCL slice_layer_rbsp( ) 2RADL_NUT Coded slice of a RADL picture or subpicture* VCLslice_layer_rbsp( ) 3 RASL_NUT Coded slice of a RASL picture orsubpicture* VCL slice_layer_rbsp( ) 4 . . . 6 RSV_VCL_4 . . . Reservednon-IRAP VCL NAL unit types VCL RSV_VCL_6 7 IDR_W_RADL Coded slice of anIDR picture or subpicture* VCL 8 IDR_N_LP slice_layer_rbsp( ) 9 CRA_NUTCoded slice of a CRA picture or subpicture* VCL silce_layer_rbsp( ) 10GDR_NUT Coded slice of a GDR picture or subpicture* VCLslice_layer_rbsp( ) 11 RSV_IRAP_11 Reserved IRAP VCL NAL unit types VCL12 RSV_IRAP_12 13 DCI_NUT Decoding capability information non-VCLdecoding_capability_information_rbsp( ) 14 VPS_NUT Video parameter setnon-VCL video_parameter_set_rbsp( ) 15 SPS_NUT Sequence parameter setnon-VCL seq_parameter_set_rbsp( ) 16 PPS_NUT Picture parameter setnon-VCL pic_parameter_set_rbsp( ) 17 PREFIX_APS_NUT Adaptation parameterset non-VCL 18 SUFFIX_APS_NUT adaptation_parameter_set_rbsp( ) 19 PH_NUTPicture header non-VCL picture_header_rbsp( ) 20 AUD_NUT AU delimiternon-VCL access_unit_delimiter_rbsp( ) 21 EOS_NUT End of sequence non-VCLend_of_seq_rbsp( ) 22 EOB_NUT End of bitstream non-VCLend_of_bitstream_rbsp( ) 23 PREFIX_SEI_NUT Supplemental enhancementinformation non-VCL 24 SUFFIX_SEI_NUT sei_rbsp( ) 25 FD_NUT Filler datanon-VCL filler_data_rbsp( ) 26 RSV_NVCL_26 Reserved non-VCL NAL unittypes non-VCL 27 RSV_NVCL_27 28 . . . 31 UNSPEC_28 . . . Unspecifiednon-VCL NAL unit types non-VCL UNSPEC_31 *indicates a property of apicture when pps_mixed_nalu_types_in_pic_flag is equal to 0 and aproperty of the subpicture when pps_mixed_nalu_types_in_pic_flag isequal to 1.NOTE—A clean random access (CRA) picture may have associated RASL orRADL pictures present in the bitstream.NOTE—An instantaneous decoding refresh (IDR) picture havingnal_unit_type equal to IDR_N_LP does not have associated leadingpictures present in the bitstream. An IDR picture having nal_unit_typeequal to IDR_W_RADL does not have associated RASL pictures present inthe bitstream, but may have associated RADL pictures in the bitstream.

The value of nal_unit_type shall be the same for all VCL NAL units of asubpicture. A subpicture is referred to as having the same NAL unit typeas the VCL NAL units of the subpicture.

When any two subpictures in a picture have different NAL unit types, thevalue of sps_subpic_treated_as_pic_flag[ ] shall be equal to 1 for allsubpictures in the picture that contain at least one P or B slice.

For VCL NAL units of any particular picture, the following applies:

-   -   If pps_mixed_nalu_types_in_pic_flag is equal to 0, the value of        nal_unit_type shall be the same for all VCL NAL units of a        picture, and a picture or a PU is referred to as having the same        NAL unit type as the coded slice NAL units of the picture or PU.    -   Otherwise (pps_mixed_nalu_types_in_pic_flag is equal to 1), the        following applies:        -   The picture shall have at least two subpictures.        -   VCL NAL units of the picture shall have two or more            different nal_unit_type values.        -   There shall be no VCL NAL unit of the picture that has            nal_unit_type_equal to GDR_NUT.        -   When the VCL NAL units of at least one subpicture of the            picture have a particular value of nal_unit_type equal to            IDR_W_RADL, IDR_N_LP, or CRA_NUT, the VCL NAL units of other            subpictures in the picture shall all have nal_unit_type            equal to TRAIL_NUT.            When vps_max_tid_il_ref_pics_plus1[i][j] is equal to 0 for j            equal to GeneralLayerIdx[nuh_layer_id] and any value of i in            the range of j+1 to vps_max_layers_minus1, inclusive, the            current picture shall not have both VCL NAL units with a            particular value of nal_unit_type equal to IDR_W_RADL,            IDR_N_LP, or CRA_NUT and VCL NAL units with nal_unit_type            equal to a different value than that particular value.            It is a requirement of bitstream conformance that the            following constraints apply:    -   When a picture is a leading picture of an IRAP picture, it shall        be a RADL or RASL picture.    -   When a subpicture is a leading subpicture of an IRAP subpicture,        it shall be a RADL or RASL subpicture.    -   When a picture is not a leading picture of an IRAP picture, it        shall not be a RADL or RASL picture.    -   When a subpicture is not a leading subpicture of an IRAP        subpicture, it shall not be a RADL or RASL subpicture.    -   No RASL pictures shall be present in the bitstream that are        associated with an IDR picture.    -   No RASL subpictures shall be present in the bitstream that are        associated with an IDR subpicture.    -   No RADL pictures shall be present in the bitstream that are        associated with an IDR picture having nal_unit_type equal to        IDR_N_LP.        -   NOTE—It is possible to perform random access at the position            of an IRAP PU by discarding all PUs before the IRAP PU (and            to correctly decode the IRAP picture and all the subsequent            non-RASL pictures in decoding order), provided each            parameter set is available (either in the bitstream or by            external means not specified in this Specification) when it            is referenced.    -   No RADL subpictures shall be present in the bitstream that are        associated with an IDR subpicture having nal_unit_type equal to        IDR_N_LP.    -   Any picture, with nuh_layer_id equal to a particular value        layerId, that precedes an IRAP picture with nuh_layer_id equal        to layerId in decoding order shall precede the IRAP picture in        output order and shall precede any RADL picture associated with        the IRAP picture in output order.    -   Any subpicture, with nuh_layer_id equal to a particular value        layerId and subpicture index equal to a particular value        subpicIdx, that precedes, in decoding order, an IRAP subpicture        with nuh_layer_id equal to layerId and subpicture index equal to        subpicIdx shall precede, in output order, the IRAP subpicture        and all its associated RADL subpictures.    -   Any picture, with nuh_layer_id equal to a particular value        layerId, that precedes a recovery point picture with        nuh_layer_id equal to layerId in decoding order shall precede        the recovery point picture in output order.    -   Any subpicture, with nuh_layer_id equal to a particular value        layerId and subpicture index equal to a particular value        subpicIdx, that precedes, in decoding order, a subpicture with        nuh_layer_id equal to layerId and subpicture index equal to        subpicIdx in a recovery point picture shall precede that        subpicture in the recovery point picture in output order.    -   Any RASL picture associated with a CRA picture shall precede any        RADL picture associated with the CRA picture in output order.    -   Any RASL subpicture associated with a CRA subpicture shall        precede any RADL subpicture associated with the CRA subpicture        in output order.    -   Any RASL picture, with nuh_layer_id equal to a particular value        layerId, associated with a CRA picture shall follow, in output        order, any IRAP or GDR picture with nuh_layer_id equal to        layerId that precedes the CRA picture in decoding order.    -   Any RASL subpicture, with nuh_layer_id equal to a particular        value layerId and subpicture index equal to a particular value        subpicIdx, associated with a CRA subpicture shall follow, in        output order, any IRAP or GDR subpicture, with nuh_layer_id        equal to layerId and subpicture index equal to subpicIdx, that        precedes the CRA subpicture in decoding order.    -   If sps_field_seq_flag is equal to 0 and the current picture,        with nuh_layer_id equal to a particular value layerId, is a        leading picture associated with an IRAP picture, it shall        precede, in decoding order, all non-leading pictures that are        associated with the same IRAP picture. Otherwise, let picA and        picB be the first and the last leading pictures, in decoding        order, associated with an IRAP picture, respectively, there        shall be at most one non-leading picture with nuh_layer_id equal        to layerId preceding picA in decoding order, and there shall be        no non-leading picture with nuh_layer_id equal to layerId        between picA and picB in decoding order.    -   If sps_field_seq_flag is equal to 0 and the current subpicture,        with nuh_layer_id equal to a particular value layerId and        subpicture index equal to a particular value subpicIdx, is a        leading subpicture associated with an IRAP subpicture, it shall        precede, in decoding order, all non-leading subpictures that are        associated with the same IRAP subpicture. Otherwise, let subpicA        and subpicB be the first and the last leading subpictures, in        decoding order, associated with an IRAP subpicture,        respectively, there shall be at most one non-leading subpicture        with nuh_layer_id equal to layerId and subpicture index equal to        subpicIdx preceding subpicA in decoding order, and there shall        be no non-leading picture with nuh_layer_id equal to layerId and        subpicture index equal to subpicIdx between picA and picB in        decoding order.

It should be noted that generally, an Intra Random Access Point (IRAP)picture is a picture that does not refer to any pictures other thanitself for prediction in its decoding process. In JVET-R2001, an IRAPpicture may be a clean random access (CRA) picture or an instantaneousdecoder refresh (IDR) picture. In JVET-R2001, the first picture in thebitstream in decoding order must be an IRAP or a gradual decodingrefresh (GDR) picture. JVET-R2001 describes the concept of a leadingpicture, which is a picture that precedes the associated IRAP picture inoutput order. JVET-R2001 further describes the concept of a trailingpicture which is a non-IRAP picture that follows the associated IRAPpicture in output order. Trailing pictures associated with an IRAPpicture also follow the IRAP picture in decoding order. For IDRpictures, there are no trailing pictures that require reference to apicture decoded prior to the IDR picture. JVET-R2001 provides where aCRA picture may have leading pictures that follow the CRA picture indecoding order and contain inter picture prediction references topictures decoded prior to the CRA picture. Thus, when the CRA picture isused as a random access point these leading pictures may not bedecodable and are identified as random access skipped leading (RASL)pictures. The other type of picture that can follow an IRAP picture indecoding order and precede it in output order is the random accessdecodable leading (RADL) picture, which cannot contain references to anypictures that precede the IRAP picture in decoding order. A GDR picture,is a picture for which each VCL NAL unit has nal_unit_type equal toGDR_NUT. If the current picture is a GDR picture that is associated witha picture header which signals a syntax element recovery_poc_cnt andthere is a picture picA that follows the current GDR picture in decodingorder in the CLVS and that has PicOrderCntVal equal to thePicOrderCntVal of the current GDR picture plus the value ofrecovery_poc_cnt, the picture picA is referred to as the recovery pointpicture.

As provided in Table 2, a NAL unit may include a video parameter set(VPS) syntax structure. Table 3 illustrates the syntax structure of thevideo parameter set provided in JVET-R2001.

TABLE 3 Descriptor video_parameter_set_rbsp( ) {vps_video_parameter_set_id u(4) vps_max_layers_minus1 u(6)vps_max_sublayers_minus1 u(3) if( vps_max_layers_minus1 > 0 &&vps_max_sublayers_minus1 > 0 ) vps_all_layers_same_num_sublayers_flagu(1) if( vps_max_layers_minus1 > 0 ) vps_all_independent_layers_flagu(1) for( i = 0; i <= vps_max_layers_minus1; i++ ) { vps_layer_id[ i ]u(6) if( i > 0 && !vps_all_independent_layers_flag ) {vps_independent_layer_flag[ i ] u(1) if( !vps_independent_layer_flag[ i] ) { vps_max_tid_ref_present_flag[ i ] u(1) for( j = 0; j < i; j++ ) {vps_direct_ref_layer_flag[ i ][ j ] u(1) if(vps_max_tid_ref_present_flag[ i ] && vps_direct_ref_layer_flag[ i ][ j ]) vps_max_tid_il_ref_pics_plus1[ i ][ j ] u(3) } } } } if(vps_max_layers_minus1 > 0 ) { if( vps_all_independent_layers_flag )vps_each_layer_is_an_ols_flag u(1) if( !vps_each_layer_is_an_ols_flag ){ if( !vps_all_independent_layers_flag ) vps_ols_mode_idc u(2) if(vps_ols_mode_idc = = 2 ) { vps_num_output_layer_sets_minus1 u(8) for( i= 1; i <= vps_num_output_layer_sets_minus1; i ++) for( j = 0; j <=vps_max_layers_minus1; j++ ) vps_ols_output_layer_flag[ i ][ j ] u(1) }} } vps_num_ptls_minus1 u(8) for( i = 0; i <= vps_num_ptls_minus1; i++ ){ if( i > 0 ) vps_pt_present_flag[ i ] u(1) if(!vps_all_layers_same_num_sublayers_flag ) vps_ptl_max_temporal_id[ i ]u(3) } while( !byte_aligned( ) ) vps_ptl_alignment_zero_bit /* equal to0 */  f(1) for( i = 0; i <= vps_num_ptls_minusl; i++ )profile_tier_level( vps_pt_present_flag[ i ], vps_ptl_max_temporal_id[ i] ) for( i = 0; i < TotalNumOlss; i++ ) if( vps_num_ptls_minus1 > 0 &&vps_num_ptls_minus1 + 1 != TotalNumOlss ) vps_ols_ptl_idx[ i ] u(8) if(!vps_each_layer_is_an_ols_flag ) { vps_num_dpb_params_minus1 ue(v)  if(vps_max_sublayers_minus1 > 0 ) vps_sublayer_dpb_params_present_flag u(1)for( i = 0; i < VpsNumDpbParams; i++ ) { if(!vps_all_layers_same_num_sublayers_flag ) vps_dpb_max_temporal_id[ i ]u(3) dpb_parameters( vps_dpb_max_temporal_id[ i ],vps_sublayer_dpb_params_present_flag ) } for( i = 0; i <NumMultiLayerOlss; i++ ) { vps_ols_dpb_pic_width[ i ] ue(v) vps_ols_dpb_pic_height[ i ] ue(v)  vps_ols_dpb_chroma_format[ i ] u(2)vps_ols_dpb_bitdepth_minus8[ i ] ue(v)  if( VpsNumDpbParams > 1 &&vps_num_dpb_params != NumMultiLayerOlss ) vps_ols_dpb_params_idx[ i ]ue(v)  } vps_general_hrd_params_present_flag u(1) } if(vps_general_hrd_params_present_flag ) { general_hrd_parameters( ) if(vps_max_sublayers_minus1 > 0 ) vps_sublayer_cpb_params_present_flag u(1)vps_num_ols_hrd_params_minus1 ue(v)  for( i = 0; i <=vps_num_ols_hrd_params_minus1; i++ ) { if(!vps_all_layers_same_num_sublayers_flag ) hrd_max_tid[ i ] u(3)firstSubLayer = vps_sublayer_cpb_params_present_flag ? 0 :vps_hrd_max_tid[ i ] ols_hrd_parameters( firstSubLayer, vps_hrd_max_tid[i ] ) } if( vps_num_ols_hrd_params_minus1 > 0 &&vps_num_ols_hrd_params_minus1 + 1 != NumMultiLayerOlss ) for( i = 0; i <NumMultiLayerOlss; i++ ) vps_ols_hrd_idx[ i ] ue(v)  }vps_extension_flag u(1) if( vps_extension_flag ) while( more_rbsp_data() ) vps_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 3, JVET-R2001 provides the following semantics:

A VPS RB SP shall be available to the decoding process prior to it beingreferenced, included in at least one AU with TemporalId equal to 0 orprovided through external means.

All VPS NAL units with a particular value of vps_video_parameter_set_idin a CVS shall have the same content.

vps_video_parameter_set_id provides an identifier for the VPS forreference by other syntax elements. The value ofvps_video_parameter_set_id shall be greater than 0.

vps_max_layers_minus1 plus 1 specifies the maximum allowed number oflayers in each CVS referring to the VPS.

vps_max_sublayers_minus1 plus 1 specifies the maximum number of temporalsublayers that may be present in a layer in each CVS referring to theVPS. The value of vps_max_sublayers_minus1 shall be in the range of 0 to6, inclusive.

vps_all_layers_same_num_sublayers_flag equal to 1 specifies that thenumber of temporal sublayers is the same for all the layers in each CVSreferring to the VPS. vps_all_layers_same_num_sublayers_flag equal to 0specifies that the layers in each CVS referring to the VPS may or maynot have the same number of temporal sublayers. When not present, thevalue of vps_all_layers_same_num_sublayers_flag is inferred to be equalto 1.vps_all_independent_layers_flag equal to 1 specifies that all layers inthe CVS are independently coded without using inter-layer prediction.vps_all_independent_layers_flag equal to 0 specifies that one or more ofthe layers in the CVS may use inter-layer prediction. When not present,the value of vps_all_independent_layers_flag is inferred to be equal to1.vps_layer_id[i] specifies the nuh_layer_id value of the i-th layer. Forany two non-negative integer values of m and n, when m is less than n,the value of vps_layer_id[m] shall be less than vps_layer_id[n].vps_independent_layer_flag[i] equal to 1 specifies that the layer withindex i does not use inter-layer prediction.vps_independent_layer_flag[i] equal to 0 specifies that the layer withindex i may use inter-layer prediction and the syntax elementsvps_direct_ref_layer_flag[i][j] for j in the range of 0 to i−1,inclusive, are present in VPS. When not present, the value ofvps_independent_layer_flag[i] is inferred to be equal to 1.vps_max_tid_ref_present_flag[i] equal to 1 specifies that the syntaxelement vps_max_tid_il_ref_pics_plus1[i][j] is present.vps_max_tid_ref_present_flag[i] equal to 0 specifies that the syntaxelement vps_max_tid_il_ref_pics_plus1[i][j] is not present.vps_direct_ref_layer_flag[i][j] equal to 0 specifies that the layer withindex j is not a direct reference layer for the layer with index i.vps_direct_ref_layer_flag [i][j] equal to 1 specifies that the layerwith index j is a direct reference layer for the layer with index i.When vps_direct_ref_layer_flag[i][j] is not present for i and j in therange of 0 to vps_max_layers_minus1, inclusive, it is inferred to beequal to 0. When vps_independent_layer_flag[i] is equal to 0, thereshall be at least one value of j in the range of 0 to i−1, inclusive,such that the value of vps_direct_ref_layer_flag[i][j] is equal to 1.The variables NumDirectRefLayers[i], DirectRefLayerIdx[i][d],NumRefLayers[i], RefLayerIdx[i][r], and LayerUsedAsRefLayerFlag[j] arederived as follows:

for( i = 0; i <= vps_max_layers_minus1; i++ ) { for(j = 0; j <=vps_max_layers_minus1; j++ ) { dependencyFlag[ i ][ j ] =vps_direct_ref_layer_flag[ i ][ j ] for( k = 0; k < i; k++ ) if(vps_direct_ref_layer_flag[ i ][ k ] && dependencyFlag[ k ][ j ] )dependencyFlag[ i ][ j ] = 1 } LayerUsedAsRefLayerFlag[ i ] = 0 } for( i= 0; i <= vps max layers minus1; i++ ) { for( j = 0, d = 0, r = 0; j <=vps_max_layers_minus1; j++ ) { if( vps_direct_ref_layer_flag[ i ][ j ] ){ DirectRefLayerIdx[ i ][ d++ ] = j LayerUsedAsRefLayerFlag[ j ] = 1 }if( dependencyFlag[ i ][ j ] ) RefLayerIdx[ i ][ r++ ] = j }NumDirectRefLayers[ i ] = d NumRefLayers[ i ] = r }The variable GeneralLayerIdx[i], specifying the layer index of the layerwith nuh_layer_id equal to vps_layer_id[i], is derived as follows:

for(i=0; i<=vps_max_layers_minus1; i++)

-   -   GeneralLayerIdx[vps_layer_id[i]]=i        For any two different values of i and j, both in the range of 0        to vps_max_layers_minus1, inclusive, when dependencyFlag[i][j]        equal to 1, it is a requirement of bitstream conformance that        the values of sps_chroma_format_idc and sps_bit_depth_minus8        that apply to the i-th layer shall be equal to the values of        sps_chroma_format_idc and sps_bit_depth_minus8, respectively,        that apply to the j-th layer.        vps_max_tid_il_ref_pics_plus1[i][j] equal to 0 specifies that        the pictures of the j-th layer that are neither IRAP pictures        nor GDR pictures with ph_recovery_poc_cnt equal to 0 are not        used as ILRPs for decoding of pictures of the i-th layer.        vps_max_tid_il_ref_pics_plus1[i][j] greater than 0 specifies        that, for decoding pictures of the i-th layer, no picture from        the j-th layer with TemporalId greater than        vps_max_tid_il_ref_pics_plus1[i][j]−1 is used as ILRP. When not        present, the value of vps_max_tid_il_ref_pics_plus1[i][j] is        inferred to be equal to vps_max_sublayers_minus1+1.        vps_each_layer_is_an_ols_flag equal to 1 specifies that each OLS        contains only one layer and each layer itself in a CVS referring        to the VPS is an OLS with the single included layer being the        only output layer. vps_each_layer_is_an_ols_flag equal to 0 that        at least one OLS contains more than one layer. If        vps_max_layers_minus1 is equal to 0, the value of        vps_each_layer_is_an_ols_flag is inferred to be equal to 1.        Otherwise, when vps_all_independent_layers_flag is equal to 0,        the value of vps_each_layer_is_an_ols_flag is inferred to be        equal to 0.        vps_ols_mode_idc equal to 0 specifies that the total number of        OLSs specified by the VPS is equal to vps_max_layers_minus1+1,        the i-th OLS includes the layers with layer indices from 0 to i,        inclusive, and for each OLS only the highest layer in the OLS is        an output layer.        vps_ols_mode_idc equal to 1 specifies that the total number of        OLSs specified by the VPS is equal to vps_max_layers_minus1+1,        the i-th OLS includes the layers with layer indices from 0 to i,        inclusive, and for each OLS all layers in the OLS are output        layers.        vps_ols_mode_idc equal to 2 specifies that the total number of        OLSs specified by the VPS is explicitly signalled and for each        OLS the output layers are explicitly signalled and other layers        are the layers that are direct or indirect reference layers of        the output layers of the OLS.        The value of vps_ols_mode_idc shall be in the range of 0 to 2,        inclusive. The value 3 of vps_ols_mode_idc is reserved for        future use by ITU-T|ISO/IEC.        When vps_all_independent_layers_flag is equal to 1 and        vps_each_layer_is_an_ols_flag is equal to 0, the value of        vps_ols_mode_idc is inferred to be equal to 2.        vps_num_output_layer_sets_minus1 plus 1 specifies the total        number of OLSs specified by the VPS when vps_ols_mode_idc is        equal to 2.        The variable TotalNumOlss, specifying the total number of OLSs        specified by the VPS, is derived as follows:

if(vps_max_layers_minus1==0)

-   -   TotalNumOlss=1

elseif(vps_each_layer_is_an_ols_flag∥vps_ols_mode_idc==0∥vps_ols_mode_idc==1)

-   -   TotalNumOlss=vps_max_layers_minus1+1

else if(vps_ols_mode_idc==2)

-   -   TotalNumOlss=vps_num_output_layer_sets_minus1+1        vps_ols_output_layer_flag[i][j] equal to 1 specifies that the        layer with nuh_layer_id equal to vps_layer_id[j] is an output        layer of the i-th OLS when vps_ols_mode_idc is equal to 2.        vps_ols_output_layer_flag[i][j] equal to 0 specifies that the        layer with nuh_layer_id equal to vps_layer_id[j] is not an        output layer of the i-th OLS when vps_ols_mode_idc is equal to        2.        The variable NumOutputLayersInOls[i], specifying the number of        output layers in the i-th OLS, the variable        NumSubLayerslnLayerInOLS[i][j], specifying the number of        sublayers in the j-th layer in the i-th OLS, the variable        OutputLayerldInOls[i][j], specifying the nuh_layer_id value of        the j-th output layer in the i-th OLS, and the variable        LayerUsedAsOutputLayerFlag[k], specifying whether the k-th layer        is used as an output layer in at least one OLS, are derived as        follows:

NumOutputLayersInOls[ 0 ] = 1 OutputLayerIdInOls[ 0 ][ 0 ] =vps_layer_id[ 0 ] NumSubLayersInLayerlnOLS[ 0 ][ 0 ] =vps_max_sub_layers_minus1 + 1 LayerUsedAsOutputLayerFlag[ 0 ] = 1 for( i= 1, i <= vps_max_layers_minus1; i++ ) { if(vps_each_layer_is_an_ols_flag || vps_ols_mode_idc < 2 )LayerUsedAsOutputLayerFlag[ i ] = 1 else /*(!vps_each_layer_is_an_ols_flag && vps_ols_mode_idc == 2) */LayerUsedAsOutputLayerFlag[ i ] = 0 } for( i = 1; i < TotalNumOlss; i++) if( vps_each_layer_is_an_ols_flag || vps_ols_mode_idc = = 0 ) {NumOutputLayersInOls[ i ] = 1 OutputLayerIdInOls[ i ][ 0 ] =vps_layer_id[ i ] if( vps_each_layer_is_an_ols_flag)NumSubLayersInLayerInOLS[ i ][ 0 ] = vps_max_sub_layers_minus1 + 1 else{ NumSubLayersInLayerInOLS[ i ][ i ] = vps_max_sub_layers_minus1 + 1for( k = i − 1, k >= 0; k− − ) { NumSubLayersInLayerInOLS[ i ][ k ] = 0for( m = k + 1; m <= i; m++ ) { maxSublayerNeeded = min(NumSubLayersInLayerInOLS[ i ][ m ], vps_max_tid_il_ref_pics_plus1[ m ][k ] ) if( vps_direct_ref_layer_flag[ m ][ k ] &&NumSubLayersInLayerInOLS[ i ][ k ] < maxSublayerNeeded )NumSubLayersInLayerInOLS[ i ][ k ] = maxSublayerNeeded } } } } else if(vps_ols_mode_idc = = 1 ) { NumOutputLayersInOls[ i ] = i + 1 for( j = 0;j < NumOutputLayersInOls[ i ]; j++ ) { OutputLayerIdInOls[ i ][ j ] =vps_layer_id[ j ] NumSubLayersInLayerInOLS[ i ][ j ] =vps_max_sub_layers_minus1 + 1 } } else if( vps_ols_mode_idc = = 2 ) {for( j = 0; j <= vps_max_layers_minus1; j++ ) { layerIncludedInOlsFlag[i ][ j ] = 0 NumSubLayersInLayerInOLS[ i ][ j ] = 0 }highestIncludedLayer = 0 numLayerInOls = 0 for( k = 0, j = 0; k <=vps_max_layers_minus1; k++ ) if( vps_ols_output_layer_flag[ i ][ k ] ) {layerIncludedInOlsFlag[ i ][ k ] = 1 highestIncludedLayer = knumLayerInOls++ LayerUsedAsOutputLayerFlag[ k ] = 1 OutputLayerIdx[ i ][j ] = k OutputLayerIdInOls[ i ][ j++ ] = vps_layer_id[ k ]NumSubLayersInLayerInOLS[ i ][ k ] = vps_max_sub_layers_minus1 + 1 }NumOutputLayersInOls[ i ] = j for( j = 0; j < NumOutputLayersInOls[ i ];j++ ) { idx = OutputLayerIdx[ i ][ j ] for( k = 0; k < NumRefLayers[ idx]; k++ ) { if (!layerIncludedInOlsFlag[ i ][ RefLayerIdx[ idx ][ k ] ] )numLayerInOls++ layerIncludedInOlsFlag[ i ][ RefLayerIdx[ idx ][ k ] ] =1 } } for( k= highestIncludedLayer − 1; k >= 0; k− − ) if(layerIncludedInOlsFlag[ i ][ k ] && !vps_ols_output_layer_flag[ i ][ k ]) for( m = k + 1; m <= highestIncludedLayer; m++ ) { maxSublayerNeeded =min( NumSubLayersInLayerInOLS[ i ][ m ], vps_max_tid_il_ref_pics_plus1[m ][ k ] ) if( vps_direct_ref_layer_flag[ m ][ k ] &&layerIncludedInOlsFlag[ i ][ m ] && NumSubLayersInLayerInOLS[ i ][ k ] <maxSublayerNeeded ) NumSubLayersInLayerInOLS[ i ][ k ] =maxSublayerNeeded } }For each value of i in the range of 0 to vps_max_layers_minus1,inclusive, the values of LayerUsedAsRefLayerFlag[i] andLayerUsedAsOutputLayerFlag[i] shall not be both equal to 0. In otherwords, there shall be no layer that is neither an output layer of atleast one OLS nor a direct reference layer of any other layer.For each OLS, there shall be at least one layer that is an output layer.In other words, for any value of i in the range of 0 to TotalNumOlss−1,inclusive, the value of NumOutputLayersInOls[i] shall be greater than orequal to 1.The variable NumLayersInOls[i], specifying the number of layers in thei-th OLS, the variable LayerldInOls[i][j], specifying the nuh_layer_idvalue of the j-th layer in the i-th OLS, and the variableNumMultiLayerOlss, specifying the number of multi-layer OLSs (i.e., OLSsthat contain more than one layer), are derived as follows:

NumLayersInOls[ 0 ] = 1 LayerIdInOls[ 0 ][ 0 ] = vps_layer_id[ 0 ]NumMultiLayerOlss = 0 for( i = 1; i < TotalNumOlss; i++ ) { if(vps_each_layer_is_an_ols_flag ) { NumLayersInOls[ i ] = 1 LayerIdInOls[i ][ 0 ] = vps_layer_id[ i ] } else if( vps_ols_mode_idc = = 0 ||vps_ols_mode_idc = = 1 ) NumLayersInOls[ i ] = i + 1 for( j = 0; j <NumLayersInOls[ i ]; j++ ) LayerIdInOls[ i ][ j ] = vps_layer_id[ j ] }else if( vps_ols_mode_idc = = 2 ) { for( k = 0, j = 0; k <=vps_max_layers_minus1; k++ ) if( layerIncludedInOlsFlag[ i ][ k ] )LayerIdInOls[ i ][ j++ ] = vps_layer_id[ k ] NumLayersInOls[ i ] = j }if( NumLayersInOls[ i ] > 1 ) { MultiLayerOlsIdx[ i ] =NumMultiLayerOlss NumMultiLayerOlss++ } } NOTE - The 0-th OLS containsonly the lowest layer (i.e., the layer with nuh_layer_id equal tovps_layer_id[ 0 ]) and for the 0-th OLS the only included layer isoutput.The variable OlsLayerIdx[i][j], specifying the OLS layer index of thelayer with nuh_layer_id equal to LayerldInOls[i][j], is derived asfollows:

for(i=0; i<TotalNumOlss; i++)

-   -   for j=0; j<NumLayersInOls[i]; j++)        -   OlsLayerIdx[i][LayerldInOls[i][j]]=j            The lowest layer in each OLS shall be an independent layer.            In other words, for each i in the range of 0 to            TotalNumOlss−1, inclusive, the value of            vps_independent_layer_flag[GeneralLayerIdx[LayerldInOls[i][0]]]            shall be equal to 1.            Each layer shall be included in at least one OLS specified            by the VPS. In other words, for each layer with a particular            value of nuh_layer_id nuhLayerId equal to one of            vps_layer_id[k] for k in the range of 0 to            vps_max_layers_minus1, inclusive, there shall be at least            one pair of values of i and j, where i is in the range of 0            to TotalNumOlss−1, inclusive, and j is in the range of            NumLayersInOls[i]−1, inclusive, such that the value of            LayerldInOls[i][j] is equal to nuhLayerId.            vps_num_ptls_minus1 plus 1 specifies the number of            profile_tier_level( ) syntax structures in the VPS. The            value of vps_num_ptls_minus1 shall be less than            TotalNumOlss.            vps_pt_present_flag[i] equal to 1 specifies that profile,            tier, and general constraints information are present in the            i-th profile_tier_level( ) syntax structure in the VPS.            vps_pt_present_flag[i] equal to 0 specifies that profile,            tier, and general constraints information are not present in            the i-th profile_tier_level( ) syntax structure in the VPS.            The value of vps_pt_present_flag[0] is inferred to be equal            to 1. When vps_pt_present_flag[i] is equal to 0, the            profile, tier, and general constraints information for the            i-th profile_tier_level( ) syntax structure in the VPS are            inferred to be the same as that for the (i−1)-th            profile_tier_level( ) syntax structure in the VPS.            vps_ptl_max_temporal_id[i] specifies the TemporalId of the            highest sublayer representation for which the level            information is present in the i-th profile_tier_level( )            syntax structure in the VPS. The value of            vps_ptl_max_temporal_id[i] shall be in the range of 0 to            vps_max_sublayers_minus1, inclusive. When not present, the            value of vps_ptl_max_temporal_id[i] is inferred to be equal            to vps_max_sublayers_minus1.            vps_ptl_alignment_zero_bit shall be equal to 0.            vps_ols_ptl_idx[i] specifies the index, to the list of            profile_tier_level( ) syntax structures in the VPS, of the            profile_tier_level( ) syntax structure that applies to the            i-th OLS. When present, the value of vps_ols_ptl_idx[i]            shall be in the range of 0 to vps_num_ptls_minus1,            inclusive.            When not present, the value of vps_ols_ptl_idx[i] is            inferred as follows:    -   If vps_num_ptls_minus1 is equal to 0, the value of        vps_ols_ptl_idx[i] is inferred to be equal to 0.    -   Otherwise (vps_num_ptls_minus1 is greater than 0 and        vps_num_ptls_minus1+1 is equal to TotalNumOlss), the value of        vps_ols_ptl_idx[i] is inferred to be equal to i.        When NumLayersInOls[i] is equal to 1, the profile_tier_level( )        syntax structure that applies to the i-th OLS is also present in        the SPS referred to by the layer in the i-th OLS. It is a        requirement of bitstream conformance that, when        NumLayersInOls[i] is equal to 1, the profile_tier_level( )        syntax structures signalled in the VPS and in the SPS for the        i-th OLS shall be identical.        Each profile_tier_level( ) syntax structure in the VPS shall be        referred to by at least one value of vps_ols_ptl_idx[i] for i in        the range of 0 to TotalNumOlss−1, inclusive.        vps_num_dpb_params_minus1 plus 1, when present, specifies the        number of dpb_parameters( ) syntax structures in the VPS. The        value of vps_num_dpb_params_minus1 shall be in the range of 0 to        NumMultiLayerOlss−1, inclusive.        The variable VpsNumDpbParams, specifying the number of        dpb_parameters( ) syntax structures in the VPS, is derived as        follows:

if(vps_each_layer_is_an_ols_flag)

-   -   VpsNumDpbParams=0

else

-   -   VpsNumDpbParams=vps_num_dpb_params_minus1+1        vps_sublayer_dpb_params_present_flag is used to control the        presence of max_dec_pic_buffering_minus1[ ],        max_num_reorder_pics[ ], and max_latency_increase_plus1[ ]        syntax elements in the dpb_parameters( ) syntax structures in        the VPS. When not present, vps_sub_dpb_params_info_present_flag        is inferred to be equal to 0.        vps_dpb_max_temporal_id[i] specifies the TemporalId of the        highest sublayer representation for which the DPB parameters may        be present in the i-th dpb_parameters( ) syntax structure in the        VPS. The value of vps_dpb_max_temporal_id[i] shall be in the        range of 0 to vps_max_sublayers_minus1, inclusive. When not        present, the value of vps_dpb_max_temporal_id[i] is inferred to        be equal to vps_max_sublayers_minus1.        vps_ols_dpb_pic_width[i] specifies the width, in units of luma        samples, of each picture storage buffer for the i-th multi-layer        OLS.        vps_ols_dpb_pic_height[i] specifies the height, in units of luma        samples, of each picture storage buffer for the i-th multi-layer        OLS.        vps_ols_dpb_chroma_format[i] specifies the greatest allowed        value of sps_chroma_format_idc for all SPSs that are referred to        by CLVSs in the CVS for the i-th multi-layer OLS.        vps_ols_dpb_bitdepth_minus8[i] specifies the greatest allowed        value of sps_bit_depth_minus8 for all SPSs that are referred to        by CLVSs in the CVS for the i-th multi-layer OLS.    -   NOTE—For decoding an OLS containing more than one layer and        having OLS index i, the deoder can safely allocate memory for        the DPB according to the values of the syntax elements        vps_ols_dpb_pic_width[i], vps_ols_dpb_pic_height[i],        vps_ols_dpb_chroma_format[i], and        vps_ols_dpb_bitdepth_minus8[i].        vps_ols_dpb_params_idx[i] specifies the index, to the list of        dpb_parameters( ) syntax structures in the VPS, of the        dpb_parameters( ) syntax structure that applies to the i-th        multi-layer OLS. When present, the value of        vps_ols_dpb_params_idx[i] shall be in the range of 0 to        VpsNumDpbParams−1, inclusive.        When vps_ols_dpb_params_idx[i] is not present, it is inferred as        follows:    -   If VpsNumDpbParams is equal to 1, the value of        vps_ols_dpb_params_idx[i] to be equal to 0.    -   Otherwise (VpsNumDpbParams is greater than 1 and equal to        NumMultiLayerOlss), the value of vps_ols_dpb_params_idx[i] is        inferred to be equal to i.        For a single-layer OLS, the applicable dpb_parameters( ) syntax        structure is present in the SPS referred to by the layer in the        OLS.        Each dpb_parameters( ) syntax structure in the VPS shall be        referred to by at least one value of vps_ols_dpb_params_idx[i]        for i in the range of 0 to NumMultiLayerOlss−1, inclusive.        vps_general_hrd_params_present_flag equal to 1 specifies that        the VPS contains a general_hrd_parameters( ) syntax structure        and other HRD parameters. vps_general_hrd_params_present_flag        equal to 0 specifies that the VPS does not contain a        general_hrd_parameters( ) syntax structure or other HRD        parameters. When not present, the value of        vps_general_hrd_params_present_flag is inferred to be equal to        0.        When NumLayersInOls[i] is equal to 1, the        general_hrd_parameters( ) syntax structure and the        ols_hrd_parameters( ) syntax structure that apply to the i-th        OLS are present in the SPS referred to by the layer in the i-th        OLS.        vps_sublayer_cpb_params_present_flag equal to 1 specifies that        the i-th ols_hrd_parameters( ) syntax structure in the VPS        contains HRD parameters for the sublayer representations with        TemporalId in the range of 0 to vps_hrd_max_tid[i], inclusive.        vps_sublayer_cpb_params_present_flag equal to 0 specifies that        the i-th ols_hrd_parameters( ) syntax structure in the VPS        contains HRD parameters for the sublayer representation with        TemporalId equal to vps_hrd_max_tid[i] only. When        vps_max_sublayers_minus1 is equal to 0, the value of        vps_sublayer_cpb_params_present_flag is inferred to be equal to        0.        When vps_sublayer_cpb_params_present_flag is equal to 0, the HRD        parameters for the sublayer representations with TemporalId in        the range of 0 to vps_hrd_max_tid[i]−1, inclusive, are inferred        to be the same as that for the sublayer representation with        TemporalId equal to vps_hrd_max_tid[i]. These include the HRD        parameters starting from the fixed_pic_rate_general_flag[i]        syntax element till the sublayer_hrd_parameters(i) syntax        structure immediately under the condition        “if(general_vcl_hrd_params_present_flag)” in the        ols_hrd_parameters syntax structure.        vps_num_ols_hrd_params_minus1 plus 1 specifies the number of        ols_hrd_parameters( ) syntax structures present in the VPS when        vps_general_hrd_params_present_flag is equal to 1. The value of        vps_num_ols_hrd_params_minus1 shall be in the range of 0 to        NumMultiLayerOlss−1, inclusive.        vps_hrd_max_tid[i] specifies the TemporalId of the highest        sublayer representation for which the HRD parameters are        contained in the i-th ols_hrd_parameters( ) syntax structure.        The value of vps_hrd_max_tid[i] shall be in the range of 0 to        vps_max_sublayers_minus1, inclusive. When not present, the value        of vps_hrd_max_tid[i] is inferred to be equal to        vps_max_sublayers_minus1.        vps_ols_hrd_idx[i] specifies the index, to the list of        ols_hrd_parameters( ) syntax structures in the VPS, of the        ols_hrd_parameters( ) syntax structure that applies to the i-th        multi-layer OLS. The value of vps_ols_hrd_idx[i] shall be in the        range of 0 to vps_num_ols_hrd_params_minus1, inclusive.        When NumLayersInOls[i] is greater than 1 and vps_ols_hrd_idx[i]        is not present, it is inferred as follows:    -   If vps_num_ols_hrd_params_minus1 is equal to 0, the value of        vps_ols_hrd_idx[[i] is inferred to be equal too.    -   Otherwise (vps_num_ols_hrd_params_minus1 is greater than 0 and        vps_num_ols_hrd_params_minus1+1 is equal to NumMultiLayerOlss),        the value of vps_ols_hrd_idx[i] is inferred to be equal to i.        For a single-layer OLS, the applicable ols_hrd_parameters( )        syntax structure is present in the SPS referred to by the layer        in the OLS.        Each ols_hrd_parameters( ) syntax structure in the VPS shall be        referred to by at least one value of vps_ols_hrd_idx[i] for i in        the range of 1 to NumMultiLayerOlss−1, inclusive.        vps_extension_flag equal to 0 specifies that no        vps_extension_data_flag syntax elements are present in the VPS        RBSP syntax structure. vps_extension_flag equal to 1 specifies        that there are vps_extension_data_flag syntax elements present        in the VPS RBSP syntax structure.        vps_extension_data_flag may have any value. Its presence and        value do not affect decoder conformance to profiles specified in        this version of this Specification. Decoders conforming to this        version of this Specification shall ignore all        vps_extension_data_flag syntax elements.

As provided in Table 2, a NAL unit may include a sequence parameter set(SPS) syntax structure. Table 4 illustrates the syntax structure of thevideo parameter set provided in JVET-R2001.

TABLE 4 Descriptor seq_parameter_set_rbsp( ) { sps_seq_parameter_set_idu(4) sps_video_parameter_set_id u(4) sps_max_sublayers_minus1 u(3)sps_reserved_zero_4bits u(4) sps_ptl_dpb_hrd_params_present_flag u(1)if( sps_ptl_dpb_hrd_params_present_flag ) profile_tier_level( 1,sps_max_sublayers_minus1 ) sps_gdr_enabled_flag u(1)sps_chroma_format_idc u(2) if( sps_chroma_format_idc = = 3 )sps_separate_colour_plane_flag u(1) sps_ref_pic_resampling_enabled_flagu(1) if( sps_ref_pic_resampling_enabled_flag )sps_res_change_in_clvs_allowed_flag u(1)sps_pic_width_max_in_luma_samples ue(v) sps_pic_height_max_in_luma_samples ue(v)  sps_conformance_window_flagu(1) if( sps_conformance_window_flag ) { sps_conf_win_left_offset ue(v) sps_conf_win_right_offset ue(v)  sps_conf_win_top_offset ue(v) sps_conf_win_bottom_offset ue(v)  } sps_log2_ctu_size_minus5 u(2)sps_subpic_info_present_flag u(1) if( sps_subpic_info_present_flag ) {sps_num_subpics_minus1 ue(v)  if( sps_num_subpics_minus1 > 0 )sps_independent_subpics_flag u(1) for( i = 0; sps_num_subpics_minus1 > 0&& i <= sps_num_subpics_minus1; i++ ) { if( i > 0 &&sps_pic_width_max_in_luma_samples > CtbSizeY )sps_subpic_ctu_top_left_x[ i ] u(v) if( i > 0 &&sps_pic_height_max_in_luma_samples > CtbSizeY ) {sps_subpic_ctu_top_left_y[ i ] u(v) if( i < sps_num_subpics_minus1 &&sps_pic_width_max_in_luma_samples > CtbSizeY ) sps_subpic_width_minus1[i ] u(v) if( i < sps_num_subpics_minus1 &&sps_pic_height_max_in_luma_samples > CtbSizeY )sps_subpic_height_minus1[ i ] u(v) if( !sps_independent_subpics_flag) {sps_subpic_treated_as_pic_flag[ i ] u(1)sps_loop_filter_across_subpic_enabled_flag[ i ] u(1) } }sps_subpic_id_len_minus1 ue(v) sps_subpic_id_mapping_explicitly_signalled_flag u(1) if(sps_subpic_id_mapping_explicitly_signalled_flag ) {sps_subpic_id_mapping_present_flag u(1) if(sps_subpic_id_mapping_present_flag ) for( i = 0; i <=sps_num_subpics_minus1; i++ ) sps_subpic_id[ i ] u(v) } }sps_bit_depth_minus8 ue(v)  sps_entropy_coding_sync_enabled_flag u(1)sps_entry_point_offsets_present_flag u(1)sps_log2_max_pic_order_cnt_lsb_minus4 u(4) sps_poc_msb_cycle_flag u(1)if( sps_poc_msb_cycle_flag ) sps_poc_msb_cycle_len_minus1 ue(v) sps_num_extra_ph_bits_bytes u(2) extra_ph_bits_struct(sps_num_extra_ph_bits_bytes ) sps_num_extra_sh_bits_bytes u(2)extra_sh_bits_struct( sps_num_extra_sh_bits_bytes ) if(sps_ptl_dpb_hrd_params_present_flag ) { if( sps_max_sublayers_minus1 > 0) sps_sublayer_dpb_params_flag u(1) dpb_parameters(sps_max_sublayers_minus1, sps_sublayer_dpb_params_flag ) } if(ChromaArrayType != 0 ) sps_qtbtt_dual_tree_intra_flag u(1)sps_log2_min_luma_coding_block_size_minus2 ue(v) sps_partition_constraints_override_enabled_flag u(1)sps_log2_diff_min_qt_min_cb_intra_slice_luma ue(v) sps_max_mtt_hierarchy_depth_intra_slice_luma ue(v)  if(sps_max_mtt_hierarchy_depth_intra_slice_luma != 0 ) {sps_log2_diff_max_bt_min_qt_intra_slice_luma ue(v) sps_log2_diff_max_tt_min_qt_intra_slice_luma ue(v)  }sps_log2_diff_min_qt_min_cb_inter_slice ue(v) sps_max_mtt_hierarchy_depth_inter_slice ue(v)  if(sps_max_mtt_hierarchy_depth_inter_slice != 0 ) {sps_log2_diff_max_bt_min_qt_inter_slice ue(v) sps_log2_diff_max_tt_min_qt_inter_slice ue(v)  } if(sps_qtbtt_dual_tree_intra_flag ) {sps_log2_diff_min_qt_min_cb_intra_slice_chroma ue(v) sps_max_mtt_hierarchy_depth_intra_slice_chroma ue(v)  if(sps_max_mtt_hierarchy_depth_intra_slice_chroma != 0 ) {sps_log2_diff_max_bt_min_qt_intra_slice_chroma ue(v) sps_log2_diff_max_tt_min_qt_intra_slice_chroma ue(v)  } } if( CtbSizeY >32 ) sps_max_luma_transform_size_64_flag u(1) if( ChromaArrayType != 0 ){ sps_joint_cbcr_enabled_flag u(1) sps_same_qp_table_for_chroma_flagu(1) numQpTables = sps_same_qp_table_for_chroma_flag ? 1 : (sps_joint_cbcr_enabled_flag ? 3 : 2 ) for( i = 0; i < numQpTables; i++ ){ sps_qp_table_start_minus26[ i ] se(v) sps_num_points_in_qp_table_minus1[ i ] ue(v)  for( j = 0; j <=sps_num_points_in_qp_table_minus1[ i ]; j++ ) {sps_delta_qp_in_val_minus1[ i ][ j ] ue(v)  sps_delta_qp_diff_val[ i ][j ] ue(v)  } } } sps_sao_enabled_flag u(1) sps_alf_enabled_flag u(1) if(sps_alf_enabled_flag && ChromaArrayType != 0 ) sps_ccalf_enabled_flagu(1) sps_transform_skip_enabled_flag u(1) if(sps_transform_skip_enabled_flag ) {sps_log2_transform_skip_max_size_minus2 ue(v)  sps_bdpcm_enabled_flagu(1) } sps_weighted_pred_flag u(1) sps_weighted_bipred_flag u(1)sps_long_term_ref_pics_flag u(1) if( sps_video_parameter_set_id > 0 )sps_inter_layer_ref_pics_present_flag u(1) sps_idr_rpl_present_flag u(1)sps_rpl1_same_as_rpl0_flag u(1) for( i = 0; i <sps_rpl1_same_as_rpl0_flag ? 1 : 2; i++ ) { sps_num_ref_pic_lists[ i ]ue(v)  for( j = 0; j < sps_num_ref_pic_lists[ i ]; j++)ref_pic_list_struct( i, j ) } sps_ref_wraparound_enabled_flag u(1)sps_temporal_mvp_enabled_flag u(1) if( sps_temporal_mvp_enabled_flag )sps_sbtmvp_enabled_flag u(1) sps_amvr_enabled_flag u(1)sps_bdof_enabled_flag u(1) if( sps_bdof_enabled_flag )sps_bdof_control_present_in_ph_flag u(1) sps_smvd_enabled_flag u(1)sps_dmvr_enabled_flag u(1) if( sps_dmvr_enabled_flag)sps_dmvr_control_present_in_ph_flag u(1) sps_mmvd_enabled_flag u(1) if(sps_mmvd_enabled_flag ) sps_mmvd_fullpel_only_flag u(1)sps_six_minus_max_num_merge_cand ue(v)  sps_sbt_enabled_flag u(1)sps_affine_enabled_flag u(1) if( sps_affine_enabled_flag ) {sps_five_minus_max_num_subblock_merge_cand ue(v)  sps_affine_type_flagu(1) if( sps_amvr_enabled_flag ) sps_affine_amvr_enabled_flag u(1)sps_affine_prof_enabled_flag u(1) if( sps_affine_prof_enabled_flag )sps_prof_control_present_in_ph_flag u(1) } sps_bcw_enabled_flag u(1)sps_ciip_enabled_flag u(1) if( MaxNumMergeCand >= 2 ) {sps_gpm_enabled_flag u(1) if( sps_gpm_enabled_flag && MaxNumMergeCand >=3 ) sps_max_num_merge_cand_minus_max_num_gpm_cand ue(v)  }sps_log2_parallel_merge_level_minus2 ue(v)  sps_isp_enabled_flag u(1)sps_mrl_enabled_flag u(1) sps_mip_enabled_flag u(1) if( ChromaArrayType!= 0 ) sps_cclm_enabled_flag u(1) if( sps_chroma_format_idc = = 1 ) {sps_chroma_horizontal_collocated_flag u(1)sps_chroma_vertical_collocated_flag u(1) } sps_mts_enabled_flag u(1) if(sps_mts_enabled_flag ) { sps_explicit_mts_intra_enabled_flag u(1)sps_explicit_mts_inter_enabled_flag u(1) } sps_palette_enabled_flag u(1)if( ChromaArrayType = = 3 && ! sps_max_luma_transform_size_64_flag )sps_act_enabled_flag u(1) if( sps_transform_skip_enabled_flag ||sps_palette_enabled_flag ) sps_internal_bit_depth_minus_input_bit_depthue(v)  sps_ibc_enabled_flag u(1) if( sps_ibc_enabled_flag )sps_six_minus_max_num_ibc_merge_cand ue(v)  sps_lmcs_enabled_flag u(1)sps_lfnst_enabled_flag u(1) sps_ladf_enabled_flag u(1) if(sps_ladf_enabled_flag ) { sps_num_ladf_intervals_minus2 u(2)sps_ladf_lowest_interval_qp_offset se(v)  for( i = 0; i <sps_num_ladf_intervals_minus2 + 1; i++ ) { sps_ladf_qp_offset[ i ]se(v)  sps_ladf_delta_threshold_minus1[ i ] ue(v)  } }sps_explicit_scaling_list_enabled_flag u(1) if( sps_lfnst_enabled_flag&& sps_explicit_scaling_list_enabled_flag )sps_scaling_matrix_for_lfnst_disabled_flag u(1) if( sps_act_enabled_flag&& sps_explicit_scaling_list_enabled_flag )sps_scaling_matrix_for_alternative_colour_space_disabled_flag u(1) if(sps_scaling_matrix_for_alternative_colour_space_disabled_flag )sps_scaling_matrix_designated_colour_space_flag u(1)sps_dep_quant_enabled_flag u(1) if( !sps_dep_quant_enabled_flag )sps_sign_data_hiding_enabled_flag u(1)sps_virtual_boundaries_enabled_flag u(1) if(sps_virtual_boundaries_enabled_flag ) {sps_virtual_boundaries_present_flag u(1) if(sps_virtual_boundaries_present_flag ) { sps_num_ver_virtual_boundariesu(2) for( i = 0; i < sps_num_ver_virtual_boundaries; i++ )sps_virtual_boundary_pos_x[ i ] ue(v)  sps_num_hor_virtual_boundariesu(2) for( i = 0; i < sps_num_hor_virtual_boundaries; i++ )sps_virtual_boundary_pos_y[ i ] ue(v)  } } if(sps_ptl_dpb_hrd_params_present_flag ) {sps_general_hrd_params_present_flag u(1) if(sps_general_hrd_params_present_flag ) { general_hrd_parameters( ) if(sps_max_sublayers_minus1 > 0 ) sps_sublayer_cpb_params_present_flag u(1)firstSubLayer = sps_sublayer_cpb_params_present_flag ? 0 :sps_max_sublayers_minus1 ols_hrd_parameters( firstSubLayer,sps_max_sublayers_minus1 ) } } sps_field_seq_flag u(1)sps_vui_parameters_present_flag u(1) if( sps_vui_parameters_present_flag) vui_parameters( ) /* Specified in ITU-T H.SEI | ISO/IEC 23002-7 */sps_extension_flag u(1) if( sps_extension_flag ) while( more_rbsp_data() ) sps_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 4, JVET-R2001 provides the following semantics:

An SPS RBSP shall be available to the decoding process prior to it beingreferenced, included in at least one AU with TemporalId equal to 0 orprovided through external means.

All SPS NAL units with a particular value of sps_seq_parameter_set_id ina CVS shall have the same content.

sps_seq_parameter_set_id provides an identifier for the SPS forreference by other syntax elements.

SPS NAL units, regardless of the nuh_layer_id values, share the samevalue space of sps_seq_parameter_set_id.

Let spsLayerId be the value of the nuh_layer_id of a particular SPS NALunit, and vclLayerId be the value of the nuh_layer_id of a particularVCL NAL unit. The particular VCL NAL unit shall not refer to theparticular SPS NAL unit unless spsLayerId is less than or equal tovclLayerId and all OLSs specified by the VPS that contain the layer withnuh_layer_id equal to vclLayerId also contain the layer withnuh_layer_id equal to spslayerId.sps_video_parameter_set_id, when greater than 0, specifies the value ofvps_video_parameter_set_id for the VPS referred to by the SPS.When sps_video_parameter_set_id is equal to 0, the following applies:

-   -   The SPS does not refer to a VPS, and no VPS is referred to when        decoding each CLVS referring to the SPS.    -   The value of vps_max_layers_minus1 is inferred to be equal to 0.    -   The value of vps_max_sublayers_minus1 is inferred to be equal to        6.    -   The CVS shall contain only one layer (i.e., all VCL NAL unit in        the CVS shall have the same value of nuh_layer_id).    -   The value of GeneralLayerIdx[nuh_layer_id] is inferred to be        equal to 0.    -   The value of        vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ] is        inferred to be equal to 1.        When vps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ]        is equal to 1, the SPS referred to by a CLVS with a particular        nuh_layer_id value nuhLayerId shall have nuh_layer_id equal to        nuhLayerId.        The value of sps_video_parameter_set_id shall be the same in all        SPSs that are referred to by CLVSs in a CVS.        sps_max_sublayers_minus1 plus 1 specifies the maximum number of        temporal sublayers that may be present in each CLVS referring to        the SPS. The value of sps_max_sublayers_minus1 shall be in the        range of 0 to vps_max_sublayers_minus1, inclusive.        sps_reserved_zero_4 bits shall be equal to 0 in bitstreams        conforming to this version of this Specification. Other values        for sps_reserved_zero_4 bits are reserved for future use by        ITU-T|ISO/IEC.        sps_ptl_dpb_hrd_params_present_flag equal to 1 specifies that a        profile_tier_level( ) syntax structure and a dpb_parameters( )        syntax structure are present in the SPS, and a        general_hrd_parameters( ) syntax structure and an        ols_hrd_parameters( ) syntax structure may also be present in        the SPS. sps_ptl_dpb_hrd_params_present_flag equal to 0        specifies that none of these four syntax structures is present        in the SPS.        When sps_video_parameter_set_id is greater than 0 and there is        an OLS that contains only one layer with nuh_layer_id equal to        the nuh_layer_id of the SPS, or when sps_video_parameter_set_id        is equal to 0, the value of sps_ptl_dpb_hrd_params_present_flag        shall be equal to 1.        sps_gdr_enabled_flag equal to 1 specifies that GDR pictures are        enabled and may be present in CLVS. sps_gdr_enabled_flag equal        to 0 specifies that GDR pictures are disabled and not present in        CLVS.        sps_chroma_format_idc specifies the chroma sampling relative to        the luma sampling as specified.        When sps_video_parameter_set_id is greater than 0 and the SPS is        referenced by a layer that is included in the i-th multi-layer        OLS specified by the VPS for any i in the range of 0 to        NumMultiLayerOlss−1, inclusive, it is a requirement of bitstream        conformance that the value of sps_chroma_format_idc shall be        less than or equal to the value of vps_ols_dpb_chroma_format[i].        sps_separate_colour_plane_flag equal to 1 specifies that the        three colour components of the 4:4:4 chroma format are coded        separately. sps_separate_colour_plane_flag equal to 0 specifies        that the colour components are not coded separately. When        sps_separate_colour_plane_flag is not present, it is inferred to        be equal to 0. When sps_separate_colour_plane_flag is equal to        1, the coded picture consists of three separate components, each        of which consists of coded samples of one colour plane (Y, Cb,        or Cr) and uses the monochrome coding syntax. In this case, each        colour plane is associated with a specific sh_colour_plane_id        value.    -   NOTE—There is no dependency in decoding processes between the        colour planes having different sh_colour_plane_id values. For        example, the decoding process of a monochrome picture with one        value of sh_colour_plane_id does not use any data from        monochrome pictures having different values of        sh_colour_plane_id for inter prediction.        Depending on the value of sps_separate_colour_plane_flag, the        value of the variable ChromaArrayType is assigned as follows:    -   If sps_separate_colour_plane_flag is equal to 0, ChromaArrayType        is set equal to sps_chroma_format_idc.    -   Otherwise (sps_separate_colour_plane_flag is equal to 1),        ChromaArrayType is set equal to 0.        sps_ref_pic_resampling_enabled_flag equal to 1 specifies that        reference picture resampling is enabled and one or more slices        of pictures in the CLVS may refer to a reference picture with a        different spatial resolution in an active entry of a reference        picture list. sps_ref_pic_resampling_enabled_flag equal to 0        specifies that reference picture resampling is disabled and no        slice of pictures in the CLVS refers to a reference picture with        a different spatial resolution in an active entry of a reference        picture list.        NOTE—When sps_ref_pic_resampling_enabled_flag is equal to 1, for        a current picture the reference picture with a different spatial        resolution may either belong to the same layer or a different        layer than the layer containing the current picture.        sps_res_change_in_clvs_allowed_flag equal to 1 specifies that        the picture spatial resolution may change within a CLVS        referring to the SPS. sps_res_change_in_clvs_allowed_flag equal        to 0 specifies that the picture spatial resolution does not        change within any CLVS referring to the SPS. When not present,        the value of sps_res_change_in_clvs_allowed_flag is inferred to        be equal to 0.        sps_pic_width_max_in_luma_samples specifies the maximum width,        in units of luma samples, of each decoded picture referring to        the SPS. sps_pic_width_max_in_luma_samples shall not be equal to        0 and shall be an integer multiple of Max(8, MinCbSizeY).        When sps_video_parameter_set_id is greater than 0 and the SPS is        referenced by a layer that is included in the i-th multi-layer        OLS specified by the VPS for any i in the range of 0 to        NumMultiLayerOlss−1, inclusive, it is a requirement of bitstream        conformance that the value of sps_pic_width_max_in_luma_samples        shall be less than or equal to the value of        vps_ols_dpb_pic_width[i].        sps_pic_height_max_in_luma_samples specifies the maximum height,        in units of luma samples, of each decoded picture referring to        the SPS. sps_pic_height_max_in_luma_samples shall not be equal        to 0 and shall be an integer multiple of Max(8, MinCbSizeY).        When sps_video_parameter_set_id is greater than 0 and the SPS is        referenced by a layer that is included in the i-th multi-layer        OLS specified by the VPS for any i in the range of 0 to        NumMultiLayerOlss−1, inclusive, it is a requirement of bitstream        conformance that the value of sps_pic_height_max_in_luma_samples        shall be less than or equal to the value of        vps_ols_dpb_pic_height[i].        sps_conformance_window_flag equal to 1 indicates that the        conformance cropping window offset parameters follow next in the        SPS. sps_conformance_window_flag equal to 0 indicates that the        conformance cropping window offset parameters are not present in        the SPS.        sps_conf_win_left_offset, sps_conf_win_right_offset,        sps_conf_win_top_offset, and sps_conf_win_bottom_offset specify        the cropping window that is applied to pictures with        pps_pic_width_in_luma_samples equal to        sps_pic_width_max_in_luma_samples and        pps_pic_height_in_luma_samples equal to        sps_pic_height_max_in_luma_samples. When        sps_conformance_window_flag is equal to 0, the values of        sps_conf_win_left_offset, sps_conf_win_right_offset,        sps_conf_win_top_offset, and sps_conf_win_bottom_offset are        inferred to be equal to 0.        The conformance cropping window contains the luma samples with        horizontal picture coordinates from        SubWidthC*sps_conf_win_left_offset to        sps_pic_width_max_in_luma_samples−(SubWidthC*sps_conf_win_right_offset+1)        and vertical picture coordinates from        SubHeightC*sps_conf_win_top_offset to        sps_pic_height_max_in_luma_samples−(SubHeightC*sps_conf_win_bottom_offset+1),        inclusive.        The value of        SubWidthC*(sps_conf_win_left_offset+sps_conf_win_right_offset)        shall be less than sps_pic_width_max_in_luma_samples, and the        value of        SubHeightC*(sps_conf_win_top_offset+sps_conf_win_bottom_offset)        shall be less than sps_pic_height_max_in_luma_samples.        When ChromaArrayType is not equal to 0, the corresponding        specified samples of the two chroma arrays are the samples        having picture coordinates (x/SubWidthC, y/SubHeightC), where        (x, y) are the picture coordinates of the specified luma        samples.    -   NOTE—The conformance cropping window offset parameters are only        applied at the output. All internal decoding processes are        applied to the uncropped picture size.        sps_log 2_ctu_size_minus5 plus 5 specifies the luma coding tree        block size of each CTU. The value of sps_log 2_ctu_size_minus5        shall be in the range of 0 to 2, inclusive. The value 3 for        sps_log 2_ctu_size_minus5 is reserved for future use by        ITU-T|ISO/IEC.        The variables CtbLog 2SizeY and CtbSizeY are derived as follows:

CtbLog 2SizeY=sps_log 2_ctu_size_minus5+5

CtbSizeY=1<<CtbLog 2SizeY

sps_subpic_info_present_flag equal to 1 specifies that subpictureinformation is present for the CLVS and there may be one or more thanone subpicture in each picture of the CLVS. sps_subpic_info_present_flagequal to 0 specifies that subpicture information is not present for theCLVS and there is only one subpicture in each picture of the CLVS.When sps_res_change_in_clvs_allowed_flag is equal to 1, the value ofsps_subpic_info_present_flag shall be equal to 0.

-   -   NOTE—When a bitstream is the result of a sub-bitstream        extraction process and contains only a subset of the subpictures        of the input bitstream to the sub-bitstream extraction process,        it might be required to set the value of        sps_subpic_info_present_flag equal to 1 in the RBSP of the SPSs.        sps_num_subpics_minus1 plus 1 specifies the number of        subpictures in each picture in the CLVS. The value of        sps_num_subpics_minus1 shall be in the range of 0 to        Ceil(sps_pic_width_max_in_luma_samples        CtbSizeY)*Ceil(sps_pic_height_max_in_luma_samples CtbSizeY)−1,        inclusive. When not present, the value of sps_num_subpics_minus1        is inferred to be equal to 0.        sps_independent_subpics_flag equal to 1 specifies that all        subpicture boundaries in the CLVS are treated as picture        boundaries and there is no loop filtering across the subpicture        boundaries. sps_independent_subpics_flag equal to 0 does not        impose such a constraint. When not present, the value of        sps_independent_subpics_flag is inferred to be equal to 1.        sps_subpic_ctu_top_left_x[i] specifies horizontal position of        top left CTU of i-th subpicture in unit of CtbSizeY. The length        of the syntax element is Ceil(Log        2((sps_pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog        2SizeY)) bits. When not present, the value of        sps_subpic_ctu_top_left_x[i] is inferred to be equal to 0.        sps_subpic_ctu_top_left_y[i] specifies vertical position of top        left CTU of i-th subpicture in unit of CtbSizeY. The length of        the syntax element is Ceil(Log        2((sps_pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog        2SizeY)) bits. When not present, the value of        sps_subpic_ctu_top_left_y[i] is inferred to be equal to 0.        sps_subpic_width_minus1[i] plus 1 specifies the width of the        i-th subpicture in units of CtbSizeY. The length of the syntax        element is Ceil(Log        2((sps_pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog        2SizeY)) bits. When not present, the value of        sps_subpic_width_minus1[i] is inferred to be equal to        ((sps_pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog        2SizeY)−sps_subpic_ctu_top_left_x[i]−1.        sps_subpic_height_minus1[i] plus 1 specifies the height of the        i-th subpicture in units of CtbSizeY. The length of the syntax        element is Ceil(Log        2((sps_pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog        2SizeY)) bits. When not present, the value of        sps_subpic_height_minus1[i] is inferred to be equal to        ((sps_pic_height_max_in_luma_samples+CtbSizeY−1)>>CtbLog        2SizeY)−sps_subpic_ctu_top_left_y[i]−1.        It is a requirement of bitstream conformance that the shapes of        the subpictures shall be such that each subpicture, when        decoded, shall have its entire left boundary and entire top        boundary consisting of picture boundaries or consisting of        boundaries of previously decoded subpictures.        For each subpicture with subpicture index i in the range of 0 to        sps_num_subpics_minus1, inclusive, it is a requirement of        bitstream conformance that all of the following conditions are        true:    -   The value of (sps_subpic_ctu_top_left_x[i] *CtbSizeY) shall be        less than        (sps_pic_width_max_in_luma_samples−sps_conf_win_right_offset*SubWidthC).    -   The value of        ((sps_subpic_ctu_top_left_x[i]+sps_subpic_width_minus1[i]+1)*CtbSizeY)        shall be greater than (sps_conf_win_left_offset*SubWidthC).    -   The value of (sps_subpic_ctu_top_left_y[i] *CtbSizeY) shall be        less than        (sps_pic_height_max_in_luma_samples−sps_conf_win_bottom_offset*SubHeightC).    -   The value of        ((sps_subpic_ctu_top_left_y[i]+sps_subpic_height_minus1[i]+1)*CtbSizeY)        shall be greater than (sps_conf_win_top_offset*SubHeightC).        sps_subpic_treated_as_pic_flag[i] equal to 1 specifies that the        i-th subpicture of each coded picture in the CLVS is treated as        a picture in the decoding process excluding in-loop filtering        operations. sps_subpic_treated_as_pic_flag[i] equal to 0        specifies that the i-th subpicture of each coded picture in the        CLVS is not treated as a picture in the decoding process        excluding in-loop filtering operations. When not present, the        value of sps_subpic_treated_as_pic_flag[i] is inferred to be        equal to 1.        When sps_num_subpics_minus1 is greater than 0 and        sps_subpic_treated_as_pic_flag[i] is equal to 1, for each CLVS        of a current layer referring to the SPS, let targetAuSet be all        the AUs starting from the AU containing the first picture of the        CLVS in decoding order, to the AU containing the last picture of        the CLVS in decoding order, inclusive, it is a requirement of        bitstream conformance that all of the following conditions are        true for the targetLayerSet that consists of the current layer        and all the layers that have the current layer as a reference        layer:    -   For each AU in targetAuSet, all pictures of the layers in        targetLayerSet shall have the same value of        pps_pic_width_in_luma_samples and the same value of        pps_pic_height_in_luma_samples.    -   All the SPSs referred to by the layers in targetLayerSet shall        have the same value of sps_num_subpics_minus1 and shall have the        same values of sps_subpic_ctu_top_left_x[j],        sps_subpic_ctu_top_left_y[j], sps_subpic_width_minus1[j],        sps_subpic_height_minus1[j], and        sps_subpic_treated_as_pic_flag[j], respectively, for each value        of j in the range of 0 to sps_num_subpics_minus1, inclusive.    -   For each AU in targetAuSet, all pictures of the layers in        targetLayerSet shall have the same value of SubpicIdVal[j] for        each value of j in the range of 0 to sps_num_subpics_minus1,        inclusive.        sps_loop_filter_across_subpic_enabled_flag[i] equal to 1        specifies that in-loop filtering operations across subpicture        boundaries is enabled and may be performed across the boundaries        of the i-th subpicture in each coded picture in the CLVS.        sps_loop_filter_across_subpic_enabled_flag[i] equal to 0        specifies that in-loop filtering operations across subpicture        boundaries is disabled and are not performed across the        boundaries of the i-th subpicture in each coded picture in the        CLVS. When not present, the value of        sps_loop_filter_across_subpic_enabled_pic_flag[i] is inferred to        be equal to 0.        sps_subpic_id_len_minus1 plus 1 specifies the number of bits        used to represent the syntax element sps_subpic_id[i], the        syntax elements pps_subpic_id[i], when present, and the syntax        element sh_subpic_id, when present. The value of        sps_subpic_id_len_minus1 shall be in the range of 0 to 15,        inclusive. The value of 1<<(sps_subpic_id_len_minus1+1) shall be        greater than or equal to sps_num_subpics_minus1+1.        sps_subpic_id_mapping_explicitly_signalled_flag equal to 1        specifies that the subpicture ID mapping is explicitly        signalled, either in the SPS or in the PPSs referred to by coded        pictures of the CLVS.        sps_subpic_id_mapping_explicitly_signalled_flag equal to 0        specifies that the subpicture ID mapping is not explicitly        signalled for the CLVS. When not present, the value of        sps_subpic_id_mapping_explicitly_signalled_flag is inferred to        be equal to 0.        sps_subpic_id_mapping_present_flag equal to 1 specifies that the        subpicture ID mapping is signalled in the SPS when        sps_subpic_id_mapping_explicitly_signalled_flag is equal to 1.        sps_subpic_id_mapping_present_flag equal to 0 specifies that        subpicture ID mapping is signalled in the PPSs referred to by        coded pictures of the CLVS when        sps_subpic_id_mapping_explicitly_signalled_flag is equal to 1.        sps_subpic_id[i] specifies the subpicture ID of the i-th        subpicture. The length of the sps_subpic_id[i] syntax element is        sps_subpic_id_len_minus1+1 bits.        sps_bit_depth_minus8 specifies the bit depth of the samples of        the luma and chroma arrays, BitDepth, and the value of the luma        and chroma quantization parameter range offset, QpBdOffset, as        follows:

BitDepth=8+sps_bit_depth_minus8

QpBdOffset=6*sps_bit_depth_minus8

sps_bit_depth_minus8 shall be in the range of 0 to 8, inclusive.

When sps_video_parameter_set_id is greater than 0 and the SPS isreferenced by a layer that is included in the i-th multi-layer OLSspecified by the VPS for any i in the range of 0 to NumMultiLayerOlss−1,inclusive, it is a requirement of bitstream conformance that the valueof sps_bit_depth_minus8 shall be less than or equal to the value ofvps_ols_dpb_bitdepth_minus8[i].sps_entropy_coding_sync_enabled_flag equal to 1 specifies that aspecific synchronization process for context variables is invoked beforedecoding the CTU that includes the first CTB of a row of CTBs in eachtile in each picture referring to the SPS, and a specific storageprocess for context variables is invoked after decoding the CTU thatincludes the first CTB of a row of CTBs in each tile in each picturereferring to the SPS. sps_entropy_coding_sync_enabled_flag equal to 0specifies that no specific synchronization process for context variablesis required to be invoked before decoding the CTU that includes thefirst CTB of a row of CTBs in each tile in each picture referring to theSPS, and no specific storage process for context variables is requiredto be invoked after decoding the CTU that includes the first CTB of arow of CTBs in each tile in each picture referring to the SPS.

-   -   NOTE—When sps_entropy_coding_sync_enabled_flag is equal to 1,        the so-called wavefront parallel processing (WPP) is enabled.        sps_entry_point_offsets_present_flag equal to 1 specifies that        signalling for entry point offsets for tiles or tile-specific        CTU rows may be present in the slice headers of pictures        referring to the SPS. sps_entry_point_offsets_present_flag equal        to 0 specifies that signalling for entry point offsets for tiles        or tile-specific CTU rows are not present in the slice headers        of pictures referring to the SPS.        sps_log 2_max_pic_order_cnt_lsb_minus4 specifies the value of        the variable MaxPicOrderCntLsb that is used in the decoding        process for picture order count as follows:

MaxPicOrderCntLsb=2^((sps_log_)2_max_pic_order_cnt_lsb_minus4+4)

The value of sps_log 2_max_pic_order_cnt_lsb_minus4 shall be in therange of 0 to 12, inclusive.

sps_poc_msb_cycle_flag equal to 1 specifies that theph_poc_msb_cycle_present_flag syntax element is present in PHs referringto the SPS. sps_poc_msb_cycle_flag equal to 0 specifies that theph_poc_msb_cycle_present_flag syntax element is not present in PHsreferring to the SPS.sps_poc_msb_cycle_len_minus1 plus 1 specifies the length, in bits, ofthe ph_poc_msb_cycle_val syntax elements, when present in the PHsreferring to the SPS. The value of sps_poc_msb_cycle_len_minus1 shall bein the range of 0 to 32−sps_log 2_max_pic_order_cnt_lsb_minus4−5,inclusive.sps_num_extra_ph_bits_bytes specifies the number of bytes of extra bitsin the PH syntax structure for coded pictures referring to the SPS. Thevalue of sps_num_extra_ph_bits_bytes shall be equal to 0 in bitstreamsconforming to this version of this Specification. Although the value ofsps_num_extra_ph_bits_bytes is required to be equal to 0 in this versionof this Specification, decoder conforming to this version of thisSpecification shall allow the value of sps_num_extra_ph_bits_bytes equalto 1 or 2 to appear in the syntax.sps_num_extra_sh_bits_bytes specifies the number of bytes of extra bitsin the slice headers for coded pictures referring to the SPS. The valueof sps_num_extra_sh_bits_bytes shall be equal to 0 in bitstreamsconforming to this version of this Specification. Although the value ofsps_num_extra_sh_bits_bytes is required to be equal to 0 in this versionof this Specification, decoder conforming to this version of thisSpecification shall allow the value of sps_num_extra_sh_bits_bytes equalto 1 or 2 to appear in the syntax.sps_sublayer_dpb_params_flag is used to control the presence ofmax_dec_pic_buffering_minus1[i], max_num_reorder_pics[i], andmax_latency_increase_plus1[i] syntax elements in the dpb_parameters( )syntax structure in the SPS. When not present, the value ofsps_sub_dpb_params_info_present_flag is inferred to be equal to 0.sps_qtbtt_dual_tree_intra_flag equal to 1 specifies that, for I slices,each CTU is split into coding units with 64×64 luma samples using animplicit quadtree split, and these coding units are the root of twoseparate coding_tree syntax structure for luma and chroma.sps_qtbtt_dual_tree_intra_flag equal to 0 specifies separate coding_treesyntax structure is not used for I slices. Whensps_qtbtt_dual_tree_intra_flag is not present, it is inferred to beequal to 0.sps_log 2_min_luma_coding_block_size_minus2 plus 2 specifies the minimumluma coding block size. The value range of sps_log2_min_luma_coding_block_size_minus2 shall be in the range of 0 to Min(4,sps_log 2_ctu_size_minus5+3), inclusive.The variables MinCbLog 2SizeY, MinCbSizeY, IbcBufWidthY, IbcBufWidthCand Vsize are derived as follows:

MinCbLog 2SizeY=sps_log 2_min_luma_coding_block_size_minus2+2

MinCbSizeY=1<<MinCbLog 2SizeY

IbcBufWidthY=256*128/CtbSizeY

IbcBufWidthC=IbcBufWidthY/SubWidthC

VSize=Min(64, CtbSizeY)

The value of MinCbSizeY shall less than or equal to VSize.

The variables CtbWidthC and CtbHeightC, which specify the width andheight, respectively, of the array for each chroma CTB, are derived asfollows:

-   -   If sps_chroma_format_idc is equal to 0 (monochrome) or        sps_separate_colour_plane_flag is equal to 1, CtbWidthC and        CtbHeightC are both equal to 0.    -   Otherwise, CtbWidthC and CtbHeightC are derived as follows:        -   CtbWidthC=CtbSizeY/SubWidthC        -   CtbHeightC=CtbSizeY/SubHeightC            For log 2BlockWidth ranging from 0 to 4 and for log            2BlockHeight ranging from 0 to 4, inclusive, the up-right            diagonal scan order array initialization process as            specified is invoked with 1<<log 2BlockWidth and 1<<log            2BlockHeight as inputs, and the output is assigned to            DiagScanOrder[log 2BlockWidth][log 2BlockHeight].            For log 2BlockWidth ranging from 0 to 6 and for log            2BlockHeight ranging from 0 to 6, inclusive, the horizontal            and vertical traverse scan order array initialization            process as specified is invoked with 1<<log 2BlockWidth and            1<<log 2BlockHeight as inputs, and the output is assigned to            HorTravScanOrder[log 2BlockWidth][log 2BlockHeight] and            VerTravScanOrder[log 2BlockWidth][log 2BlockHeight].            sps_partition_constraints_override_enabled_flag equal to 1            specifies the presence of            ph_partition_constraints_override_flag in PHs referring to            the SPS. sps_partition_constraints_override_enabled_flag            equal to 0 specifies the absence of            ph_partition_constraints_override_flag in PHs referring to            the SPS.            sps_log 2_diff_min_qt_min_cb_intra_slice_luma specifies the            default difference between the base 2 logarithm of the            minimum size in luma samples of a luma leaf block resulting            from quadtree splitting of a CTU and the base 2 logarithm of            the minimum coding block size in luma samples for luma CUs            in slices with sh_slice_type equal to 2 (I) referring to the            SPS. When sps_partition_constraints_override_enabled_flag is            equal to 1, the default difference can be overridden by            ph_log 2_diff_min_qt_min_cb_luma present in PHs referring to            the SPS. The value of sps_log            2_diff_min_qt_min_cb_intra_slice_luma shall be in the range            of 0 to Min(6, CtbLog 2SizeY)−MinCbLog 2SizeY, inclusive.            The base 2 logarithm of the minimum size in luma samples of            a luma leaf block resulting from quadtree splitting of a CTU            is derived as follows:

MinQtLog 2SizeIntraY=sps_log2_diff_min_qt_min_cb_intra_slice_luma+MinCbLog 2SizeY

sps_max_mtt_hierarchy_depth_intra_slice_luma specifies the defaultmaximum hierarchy depth for coding units resulting from multi-type treesplitting of a quadtree leaf in slices with sh_slice_type equal to 2 (I)referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault maximum hierarchy depth can be overridden byph_max_mtt_hierarchy_depth_intra_slice_luma present in PHs referring tothe SPS. The value of sps_max_mtt_hierarchy_depth_intra_slice_luma shallbe in the range of 0 to 2*(CtbLog 2SizeY−MinCbLog 2SizeY), inclusive.sps_log 2_diff_max_bt_min_qt_intra_slice_luma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a luma coding block that can be split using abinary split and the minimum size (width or height) in luma samples of aluma leaf block resulting from quadtree splitting of a CTU in sliceswith sh_slice_type equal to 2 (I) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log 2_diff_max_bt_min_qt_lumapresent in PHs referring to the SPS. The value of sps_log2_diff_max_bt_min_qt_intra_slice_luma shall be in the range of 0 to(sps_qtbtt_dual_tree_intra_flag ? Min(6, CtbLog 2SizeY):CtbLog2SizeY)−MinQtLog 2SizeIntraY, inclusive. When sps_log2_diff_max_bt_min_qt_intra_slice_luma is not present, the value ofsps_log 2_diff_max_bt_min_qt_intra_slice_luma is inferred to be equal to0.sps_log 2_diff_max_tt_min_qt_intra_slice_luma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a luma coding block that can be split using aternary split and the minimum size (width or height) in luma samples ofa luma leaf block resulting from quadtree splitting of a CTU in sliceswith sh_slice_type equal to 2 (I) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log 2_diff_max_n_min_qt_lumapresent in PHs referring to the SPS. The value of sps_log2_diff_max_tt_min_qt_intra_slice_luma shall be in the range of 0 toMin(6, CtbLog 2SizeY)−MinQtLog 2SizeIntraY, inclusive. When sps_log2_diff_max_n_min_qt_intra_slice_luma is not present, the value ofsps_log 2_diff_max_tt_min_qt_intra_slice_luma is inferred to be equal to0.sps_log 2_diff_min_qt_min_cb_inter_slice specifies the defaultdifference between the base 2 logarithm of the minimum size in lumasamples of a luma leaf block resulting from quadtree splitting of a CTUand the base 2 logarithm of the minimum luma coding block size in lumasamples for luma CUs in slices with sh_slice_type equal to 0 (B) or 1(P) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log 2_diff_min_qt_min_cb_lumapresent in PHs referring to the SPS. The value of sps_log2_diff_min_qt_min_cb_inter_slice shall be in the range of 0 to Min(6,CtbLog 2SizeY)−MinCbLog 2SizeY, inclusive. The base 2 logarithm of theminimum size in luma samples of a luma leaf block resulting fromquadtree splitting of a CTU is derived as follows:

MinQtLog 2SizeInterY=sps_log 2_diff_min_qt_min_cb_inter_slice+MinCbLog2SizeY

sps_max_mtt_hierarchy_depth_inter_slice specifies the default maximumhierarchy depth for coding units resulting from multi-type treesplitting of a quadtree leaf in slices with sh_slice_type equal to 0 (B)or 1 (P) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault maximum hierarchy depth can be overridden byph_max_mtt_hierarchy_depth_inter_slice present in PHs referring to theSPS. The value of sps_max_mtt_hierarchy_depth_inter_slice shall be inthe range of 0 to 2*(CtbLog 2SizeY−MinCbLog 2SizeY), inclusive.sps_log 2_diff_max_bt_min_qt_inter_slice specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a luma coding block that can be split using abinary split and the minimum size (width or height) in luma samples of aluma leaf block resulting from quadtree splitting of a CTU in sliceswith sh_slice_type equal to 0 (B) or 1 (P) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log 2_diff_max_bt_min_qt_lumapresent in PHs referring to the SPS. The value of sps_log2_diff_max_bt_min_qt_inter_slice shall be in the range of 0 to CtbLog2SizeY−MinQtLog 2SizeInterY, inclusive. When sps_log2_diff_max_bt_min_qt_inter_slice is not present, the value of sps_log2_diff_max_bt_min_qt_inter_slice is inferred to be equal to 0.sps_log 2_diff_max_tt_min_qt_inter_slice specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a luma coding block that can be split using aternary split and the minimum size (width or height) in luma samples ofa luma leaf block resulting from quadtree splitting of a CTU in sliceswith sh_slice_type equal to 0 (B) or 1 (P) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log 2_diff_max_n_min_qt_lumapresent in PHs referring to the SPS. The value of sps_log2_diff_max_tt_min_qt_inter_slice shall be in the range of 0 to Min(6,CtbLog 2SizeY)−MinQtLog 2SizeInterY, inclusive. When sps_log2_diff_max_tt_min_qt_inter_slice is not present, the value of sps_log2_diff_max_tt_min_qt_inter_slice is inferred to be equal to 0.sps_log 2_diff_min_qt_min_cb_intra_slice_chroma specifies the defaultdifference between the base 2 logarithm of the minimum size in lumasamples of a chroma leaf block resulting from quadtree splitting of achroma CTU with treeType equal to DUAL_TREE_CHROMA and the base 2logarithm of the minimum coding block size in luma samples for chromaCUs with treeType equal to DUAL_TREE_CHROMA in slices with sh_slice_typeequal to 2 (I) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log2_diff_min_qt_min_cb_chroma present in PHs referring to the SPS. Thevalue of sps_log 2_diff_min_qt_min_cb_intra_slice_chroma shall be in therange of 0 to Min(6, CtbLog 2SizeY)−MinCbLog 2SizeY, inclusive. When notpresent, the value of sps_log 2_diff_min_qt_min_cb_intra_slice_chroma isinferred to be equal to 0. The base 2 logarithm of the minimum size inluma samples of a chroma leaf block resulting from quadtree splitting ofa CTU with treeType equal to DUAL_TREE_CHROMA is derived as follows:

MinQtLog 2SizeIntraC=sps_log2_diff_min_qt_min_cb_intra_slice_chroma+MinCbLog 2SizeY

sps_max_mtt_hierarchy_depth_intra_slice_chroma specifies the defaultmaximum hierarchy depth for chroma coding units resulting frommulti-type tree splitting of a chroma quadtree leaf with treeType equalto DUAL_TREE_CHROMA in slices with sh_slice_type equal to 2 (I)referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault maximum hierarchy depth can be overridden byph_max_mtt_hierarchy_depth_chroma present in PHs referring to the SPS.The value of sps_max_mtt_hierarchy_depth_intra_slice_chroma shall be inthe range of 0 to 2*(CtbLog 2SizeY−MinCbLog 2SizeY), inclusive. When notpresent, the value of sps_max_mtt_hierarchy_depth_intra_slice_chroma isinferred to be equal to 0.sps_log 2_diff_max_bt_min_qt_intra_slice_chroma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a chroma coding block that can be split usinga binary split and the minimum size (width or height) in luma samples ofa chroma leaf block resulting from quadtree splitting of a chroma CTUwith treeType equal to DUAL_TREE_CHROMA in slices with sh_slice_typeequal to 2 (I) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log2_diff_max_bt_min_qt_chroma present in PHs referring to the SPS. Thevalue of sps_log 2_diff_max_bt_min_qt_intra_slice_chroma shall be in therange of 0 to Min(6, CtbLog 2SizeY)−MinQtLog 2SizeIntraC, inclusive.When sps_log 2_diff_max_bt_min_qt_intra_slice_chroma is not present, thevalue of sps_log 2_diff_max_bt_min_qt_intra_slice_chroma is inferred tobe equal to 0.sps_log 2_diff_max_tt_min_qt_intra_slice_chroma specifies the defaultdifference between the base 2 logarithm of the maximum size (width orheight) in luma samples of a chroma coding block that can be split usinga ternary split and the minimum size (width or height) in luma samplesof a chroma leaf block resulting from quadtree splitting of a chroma CTUwith treeType equal to DUAL_TREE_CHROMA in slices with sh_slice_typeequal to 2 (I) referring to the SPS. Whensps_partition_constraints_override_enabled_flag is equal to 1, thedefault difference can be overridden by ph_log2_diff_max_n_min_qt_chroma present in PHs referring to the SPS. Thevalue of sps_log 2_diff_max_tt_min_qt_intra_slice_chroma shall be in therange of 0 to Min(6, CtbLog 2SizeY)−MinQtLog 2SizeIntraC, inclusive.When sps_log 2_diff_max_tt_min_qt_intra_slice_chroma is not present, thevalue of sps_log 2_diff_max_tt_min_qt_intra_slice_chroma is inferred tobe equal to 0.sps_max_luma_transform_size_64_flag equal to 1 specifies that themaximum transform size in luma samples is equal to 64.sps_max_luma_transform_size_64_flag equal to 0 specifies that themaximum transform size in luma samples is equal to 32. When not present,the value of sps_max_luma_transform_size_64_flag is inferred to be equalto 0.The variables MinTbLog 2SizeY, MaxTbLog 2SizeY, MinTbSizeY, andMaxTbSizeY are derived as follows:

MinTbLog 2SizeY=2

MaxTbLog 2SizeY=sps_max_luma_transform_size_64_flag ? 6:5

MinTbSizeY=1<<MinTbLog 2SizeY

MaxTbSizeY=1<<MaxTbLog 2SizeY

sps_joint_cbcr_enabled_flag equal to 0 specifies that the joint codingof chroma residuals is disabled and not used in decoding of pictures inthe CLVS. sps_joint_cbcr_enabled_flag equal to 1 specifies that thejoint coding of chroma residuals is enabled and may be used in decodingof pictures in the CLVS. When not present, the value ofsps_joint_cbcr_enabled_flag is inferred to be equal to 0.sps_same_qp_table_for_chroma_flag equal to 1 specifies that only onechroma QP mapping table is signalled and this table applies to Cb and Crresiduals and additionally to joint Cb-Cr residuals whensps_joint_cbcr_enabled_flag is equal to 1.sps_same_qp_table_for_chroma_flag equal to 0 specifies that chroma QPmapping tables, two for Cb and Cr, and one additional for joint Cb-Crwhen sps_joint_cbcr_enabled_flag is equal to 1, are signalled in theSPS. When not present, the value of sps_same_qp_table_for_chroma_flag isinferred to be equal to 1.sps_qp_table_start_minus26[i] plus 26 specifies the starting luma andchroma QP used to describe the i-th chroma QP mapping table. The valueof sps_qp_table_start_minus26[i] shall be in the range of −26−QpBdOffsetto 36 inclusive. When not present, the value ofsps_qp_table_start_minus26[i] is inferred to be equal to 0.sps_num_points_in_qp_table_minus1[i] plus 1 specifies the number ofpoints used to describe the i-th chroma QP mapping table. The value ofsps_num_points_in_qp_table_minus1[i] shall be in the range of 0 to63+QpBdOffset, inclusive. When not present, the value ofsps_num_points_in_qp_table_minus1 [0] is inferred to be equal to 0.sps_delta_qp_in_val_minus1[i][j] specifies a delta value used to derivethe input coordinate of the j-th pivot point of the i-th chroma QPmapping table. When not present, the value of sps_delta_qp_in_val_minus1[0][j] is inferred to be equal to 0.sps_delta_qp_diff_val[i][j] specifies a delta value used to derive theoutput coordinate of the j-th pivot point of the i-th chroma QP mappingtable.The i-th chroma QP mapping table ChromaQpTable[I] for I=0 . . .numQpTables−1 is derived as follows:

qpInVal[ i ][ 0 ] = sps_qp_table_start_minus26[ i ] + 26 qpOutVal[ i ][0 ] = qpInVal[ i ][ 0 ] for(j = 0;j <=sps_num_points_in_qp_table_minus1[ i ]; j++ ) { qpInVal[ i ][ j + 1 ] =qpInVal[ i ][ j ] + sps_delta_qp_in_val_minus1[ i ][ j ] + 1 qpOutVal[ i][ j + 1 ] = qpOutVal[ i ][ j ] + ( sps_delta_qp_in_val_minus1[ i ][ j ]{circumflex over ( )} sps_delta_qp_diff_val[ i ][ j ] ) } ChromaQpTable[i ][ qpInVal[ i ][ 0 ] ] = qpOutVal[ i ][ 0 ] for( k = qpInVal[ i ][ 0 ]− 1; k >= −QpBdOffset; k − − ) ChromaQpTable[ i ][ k ] = Clip3(−QpBdOffset, 63, ChromaQpTable[ i ][ k + 1 ] − 1 ) for( j = 0; j <=sps_num_points_in_qp_table_minus1[ i ]; j++ ) { sh = (sps_delta_qp_in_val_minus1[ i ][j ] + 1 ) >> 1 for( k = qpInVal[ i ][ j] + 1, m = 1; k <= qpInval[ i ][ j + 1 ]; k++, m++ ) ChromaQpTable[ i ][k ] = ChromaQpTable[ i ][ qpInVal[ i ][ j ] ] + ((qp } for( k = qpInVal[i ][ sps_num_points_in_qp_table_minus1[ i ] + 1 ] + 1; k <= 63; k++ )ChromaQpTable[ i ][ k ] = Clip3( −QpBdOffset, 63, ChromaQpTable[ i ][ k− 1 ] + 1 )When sps_same_qp_table_for_chroma_flag is equal to 1,ChromaQpTable[1][k] and ChromaQpTable[2][k] are set equal toChromaQpTable[0][k] for kin the range of −QpBdOffset to 63, inclusive.It is a requirement of bitstream conformance that the values ofqpInVal[i][j] and qpOutVal[i][j] shall be in the range of −QpBdOffset to63, inclusive for i in the range of 0 to numQpTables−1, inclusive, and jin the range of 0 to sps_num_points_in_qp_table_minus1[i]+1, inclusive.sps_sao_enabled_flag equal to 1 specifies that the sample adaptiveoffset process is enabled and may be applied to the reconstructedpicture after the deblocking filter process for the CLVS.sps_sao_enabled_flag equal to 0 specifies that the sample adaptiveoffset process is disabled and not applied to the reconstructed pictureafter the deblocking filter process for the CLVS.sps_alf_enabled_flag equal to 0 specifies that the adaptive loop filteris disabled and not applied in decoding of pictures in the CLVS.sps_alf_enabled_flag equal to 1 specifies that the adaptive loop filteris enabled and may be applied in decoding of pictures in the CLVS.sps_ccalf_enabled_flag equal to 0 specifies that the cross-componentadaptive loop filter is disabled and not applied in decoding of picturesin the CLVS. sps_ccalf_enabled_flag equal to 1 specifies that thecross-component adaptive loop filter is enabled and may be applied indecoding of pictures in the CLVS. When not present, the value ofsps_ccalf_enabled_flag is inferred to be equal to 0.sps_transform_skip_enabled_flag equal to 1 specifies thattransform_skip_flag may be present in the transform unit syntax.sps_transform_skip_enabled_flag equal to 0 specifies thattransform_skip_flag is not present in the transform unit syntax.sps_log 2_transform_skip_max_size_minus2 specifies the maximum blocksize used for transform skip, and shall be in the range of 0 to 3,inclusive.The variable MaxTsSize is set equal to 1<<(sps_log2_transform_skip_max_size_minus2+2). sps_bdpcm_enabled_flag equal to 1specifies that intra_bdpcm_luma_flag and intra_bdpcm_chroma_flag may bepresent in the coding unit syntax for intra coding units.sps_bdpcm_enabled_flag equal to 0 specifies that intra_bdpcm_luma_flagand intra_bdpcm_chroma_flag are not present in the coding unit syntaxfor intra coding units. When not present, the value ofsps_bdpcm_enabled_flag is inferred to be equal to 0.sps_weighted_pred_flag equal to 1 specifies that weighted prediction maybe applied to P slices referring to the SPS. sps_weighted_pred_flagequal to 0 specifies that weighted prediction is not applied to P slicesreferring to the SPS.sps_weighted_bipred_flag equal to 1 specifies that explicit weightedprediction may be applied to B slices referring to the SPS.sps_weighted_bipred_flag equal to 0 specifies that explicit weightedprediction is not applied to B slices referring to the SPS.sps_long_term_ref_pics_flag equal to 0 specifies that no LTRP is usedfor inter prediction of any coded picture in the CLVS.sps_long_term_ref_pics_flag equal to 1 specifies that LTRPs may be usedfor inter prediction of one or more coded pictures in the CLVS.sps_inter_layer_ref_pics_present_flag equal to 0 specifies that no ILRPis used for inter prediction of any coded picture in the CLVS.sps_inter_layer_ref_pics_present_flag equal to 1 specifies that ILRPsmay be used for inter prediction of one or more coded pictures in theCLVS. When sps_video_parameter_set_id is equal to 0, the value ofsps_inter_layer_ref_pics_present_flag is inferred to be equal to 0. Whenvps_independent_layer_flag[GeneralLayerIdx[nuh_layer_id] ] is equal to1, the value of sps_inter_layer_ref_pics_present_flag shall be equal to0.sps_idr_rpl_present_flag equal to 1 specifies that reference picturelist syntax elements are present in slice headers of IDR pictures.sps_idr_rpl_present_flag equal to 0 specifies that reference picturelist syntax elements are not present in slice headers of IDR pictures.sps_rpl1_same_as_rpl0_flag equal to 1 specifies that the syntax elementsps_num_ref_pic_lists[1] and the syntax structure ref_pic_list_struct(1,rplsIdx) are not present and the following applies:The value of sps_num_ref_pic_lists[1] is inferred to be equal to thevalue of sps_num_ref_pic_lists[0].The value of each of syntax elements in ref_pic_list_struct(1, rplsIdx)is inferred to be equal to the value of corresponding syntax element inref_pic_list_struct(0, rplsIdx) for rplsIdx ranging from 0 tosps_num_ref_pic_lists[0]−1.sps_num_ref_pic_lists[i] specifies the number of theref_pic_list_struct(listIdx, rplsIdx) syntax structures with listIdxequal to i included in the SPS. The value of sps_num_ref_pic_lists[i]shall be in the range of 0 to 64, inclusive.

-   -   NOTE—For each value of listIdx (equal to 0 or 1), a decoder        should allocate memory for a total number of        sps_num_ref_pic_lists[i]+1 ref_pic_list_struct(listIdx, rplsIdx)        syntax structures since there may be one        ref_pic_list_struct(listIdx, rplsIdx) syntax structure directly        signalled in the slice headers of a current picture.        sps_ref_wraparound_enabled_flag equal to 1 specifies that        horizontal wrap-around motion compensation is enabled and may be        applied in inter prediction when decoding pictures in the CLVS.        sps_ref_wraparound_enabled_flag equal to 0 specifies that        horizontal wrap-around motion compensation is disabled and not        applied in inter prediction when decoding pictures in the CLVS.        It is a requirement of bitstream conformance that, when there is        one or more values of i in the range of 0 to        sps_num_subpics_minus1, inclusive, for which        sps_subpic_treated_as_pic_flag[i] is equal to 1 and        sps_subpic_width_minus1[i] plus 1 is not equal to        (sps_pic_width_max_in_luma_samples+CtbSizeY−1)>>CtbLog 2SizeY),        the value of sps_ref_wraparound_enabled_flag shall be equal to        0.        sps_temporal_mvp_enabled_flag equal to 1 specifies that temporal        motion vector predictors are enabled and may be used in decoding        of pictures in the CLVS. sps_temporal_mvp_enabled_flag equal to        0 specifies that temporal motion vector predictors are disabled        and not used in decoding of pictures in the CLVS.        sps_sbtmvp_enabled_flag equal to 1 specifies that subblock-based        temporal motion vector predictors are enabled and may be used in        decoding of pictures with all slices having sh_slice_type not        equal to I in the CLVS.        sps_sbtmvp_enabled_flag equal to 0 specifies that subblock-based        temporal motion vector predictors are disabled and not used in        decoding of pictures in the CLVS. When sps_sbtmvp_enabled_flag        is not present, it is inferred to be equal to 0.        sps_amvr_enabled_flag equal to 1 specifies that adaptive motion        vector difference resolution is enabled and may be used in        motion vector coding in decoding of pictures in the CVLS.        amvr_enabled_flag equal to 0 specifies that adaptive motion        vector difference resolution is disabled and not used in motion        vector coding in decoding of pictures in the CLVS.        sps_bdof_enabled_flag equal to 0 specifies that the        bi-directional optical flow inter prediction is disabled and not        used in decoding of pictures in the CLVS. sps_bdof_enabled_flag        equal to 1 specifies that the bi-directional optical flow inter        prediction is enabled and may be used in decoding of pictures in        the CLVS.        sps_bdof_control_present_in_ph_flag equal to 1 specifies that        ph_bdof_disabled_flag is present in PHs referring to the SPS.        sps_bdof_control_present_in_ph_flag equal to 0 specifies that        ph_bdof_disabled_flag is not present in PHs referring to the        SPS. When sps_bdof_control_present_in_ph_flag is not present,        the value of sps_bdof_control_present_in_ph_flag is inferred to        be equal to 0.        sps_smvd_enabled_flag equal to 1 specifies that symmetric motion        vector difference is enabled may be used in motion vector        decoding in decoding of pictures in the CLVS.        sps_smvd_enabled_flag equal to 0 specifies that symmetric motion        vector difference is disabled and not used in motion vector        coding in decoding of pictures in the CLVS.        sps_dmvr_enabled_flag equal to 1 specifies that decoder motion        vector refinement based inter bi-prediction is enabled and may        be used in decoding of pictures in the CLVS.        sps_dmvr_enabled_flag equal to 0 specifies that decoder motion        vector refinement based inter bi-prediction is disabled and not        used in decoding of pictures in the CLVS.        sps_dmvr_control_present_in_ph_flag equal to 1 specifies that        ph_dmvr_disabled_flag is present in PHs referring to the SPS.        sps_dmvr_control_present_in_ph_flag equal to 0 specifies that        ph_dmvr_disabled_flag is not present in PHs referring to the        SPS. When sps_dmvr_control_present_in_ph_flag is not present,        the value of sps_dmvr_control_present_in_ph_flag is inferred to        be equal to 0.        sps_mmvd_enabled_flag equal to 1 specifies that merge mode with        motion vector difference is enabled and may be used in decoding        of pictures in the CLVS. sps_mmvd_enabled_flag equal to 0        specifies that merge mode with motion vector difference is        disabled and not used in in decoding of pictures in the CLVS.        sps_six_minus_max_num_merge_cand specifies the maximum number of        merging motion vector prediction (MVP) candidates supported in        the SPS subtracted from 6. The value of        sps_six_minus_max_num_merge_cand shall be in the range of 0 to        5, inclusive.        The maximum number of merging MVP candidates, MaxNumMergeCand,        is derived as follows:

MaxNumMergeCand=6−sps_six_minus_max_num_merge_cand

sps_sbt_enabled_flag equal to 0 specifies that subblock transform forinter-predicted CUs is disabled and not used in decoding of pictures inthe CLVS. sps_sbt_enabled_flag equal to 1 specifies that subblocktransform for inter-predicteds CU is enabled and may be used in decodingof pictures in the CLVS.sps_affine_enabled_flag equal to 0 specifies that affine model basedmotion compensation is disabled and not used in decoding of pictures inthe CLVS and inter_affine_flag and cu_affine_type_flag are not presentin the coding unit syntax of the CLVS. sps_affine_enabled_flag equal to1 specifies that affine model based motion compensation is enabled andmay be used in decoding of pictures in the CLVS and inter_affine_flagand cu_affine_type_flag may be present in the coding unit syntax of theCLVS.sps_five_minus_max_num_subblock_merge_cand specifies the maximum numberof subblock-based merging motion vector prediction candidates supportedin the SPS subtracted from 5. The value ofsps_five_minus_max_num_subblock_merge_cand shall be in the range of 0 to5−sps_sbtmvp_enabled_flag, inclusive.sps_affine_type_flag specifies whether 6-parameter affine model basedmotion compensation can be used for inter prediction. Ifsps_affine_type_flag is equal to 0, the syntax shall be constrained suchthat no 6-parameter affine model based motion compensation is used inthe CLVS, and cu_affine_type_flag is not present in coding unit syntaxin the CLVS. Otherwise (sps_affine_type_flag is equal to 1), 6-parameteraffine model based motion compensation can be used in the CLVS. When notpresent, the value of sps_affine_type_flag is inferred to be equal to 0.sps_affine_amvr_enabled_flag equal to 1 specifies that adaptive motionvector difference resolution is enabled and may be used in motion vectorcoding of affine inter mode in decoding of pictures in the CLVS.sps_affine_amvr_enabled_flag equal to 0 specifies that adaptive motionvector difference resolution is disabled and not used in motion vectorcoding of affine inter mode in decoding of pictures in the CLVS. Whennot present, the value of sps_affine_amvr_enabled_flag is inferred to beequal to 0.sps_affine_prof_enabled_flag equal to 0 specifies that the affine motioncompensation refined with optical flow is disabled and not used indecoding of pictures in the CLVS. sps_affine_prof_enabled_flag equal to1 specifies that the affine motion compensation refined with opticalflow is enabled and may be used in decoding of pictures in the CLVS.When not present, the value of sps_affine_prof_enabled_flag is inferredto be equal to 0.sps_prof_control_present_in_ph_flag equal to 1 specifies thatph_prof_disabled_flag is present in PHs referring to the SPS.sps_prof_control_present_in_ph_flag equal to 0 specifies thatph_prof_disabled_flag is not present in PHs referring to the SPS. Whensps_prof_control_present_in_ph_flag is not present, the value ofsps_prof_control_present_in_ph_flag is inferred to be equal to 0.sps_bcw_enabled_flag equal to 0 specifies that bi-prediction with CUweights is disabled and not used in decoding of pictures in the CLVS andbcw_idx is not present in the coding unit syntax of the CLVS.sps_bcw_enabled_flag equal to 1 specifies that bi-prediction with CUweights is enabled and may be used in decoding of pictures in the CLVSand bcw_idx may be present in the coding unit syntax of the CLVS.sps_ciip_enabled_flag specifies that ciip_flag may be present in thecoding unit syntax for inter coding units. sps_ciip_enabled_flag equalto 0 specifies that ciip_flag is not present in the coding unit syntaxfor inter coding units.sps_mmvd_fullpel_only_flag equal to 1 specifies that merge mode withmotion vector difference uses integer sample precision.sps_mmvd_fullpel_only_flag equal to 0 specifies that merge mode withmotion vector difference may use fractional sample precision. When notpresent, the value of sps_mmvd_fullpel_only_flag is inferred to be equalto 0.sps_gpm_enabled_flag equal to 0 specifies that geometric partition basedmotion compensation is disabled and not used in decoding of picturs inthe CLVS and merge_gpm_partition_idx, merge_gpm_idx0, and merge_gpm_idx1are not present in the coding unit syntax of the CLVS.sps_gpm_enabled_flag equal to 1 specifies that geometric partition basedmotion compensation is enabled and may be used in decoding of picturesin the CLVS and merge_gpm_partition_idx, merge_gpm_idx0, andmerge_gpm_idx1 may be present in the coding unit syntax of the CLVS.When not present, the value of sps_gpm_enabled_flag is inferred to beequal to 0.sps_max_num_merge_cand_minus_max_num_gpm_cand specifies the maximumnumber of geometric partitioning merge mode candidates supported in theSPS subtracted from MaxNumMergeCand. The value ofsps_max_num_merge_cand_minus_max_num_gpm_cand shall be in the range of 0to MaxNumMergeCand−2, inclusive.The maximum number of geometric partitioning merge mode candidates,MaxNumGpmMergeCand, is derived as follows:

if(sps_gpm_enabled_flag && MaxNumMergeCand>=3)

-   -   MaxNumGpmMergeCand=MaxNumMergeCand−        -   sps_max_num_merge_cand_minus_max_num_gpm_cand

else if(sps_gpm_enabled_flag && MaxNumMergeCand==2)

-   -   MaxNumGpmMergeCand=2

else

-   -   MaxNumGpmMergeCand=0        sps_log 2_parallel_merge_level_minus2 plus 2 specifies the value        of the variable Log 2ParMrgLevel, which is used in the        derivation process for spatial merging candidates as specified,        the derivation process for motion vectors and reference indices        in subblock merge mode as specified, and to control the        invocation of the updating process for the history-based motion        vector predictor list. The value of sps_log        2_parallel_merge_level_minus2 shall be in the range of 0 to        CtbLog 2SizeY−2, inclusive. The variable Log 2ParMrgLevel is        derived as follows:

Log 2ParMrgLevel=sps_log 2_parallel_merge_level_minus2+2

sps_isp_enabled_flag equal to 1 specifies that intra prediction withsubpartitions is enabled and may be used in decoding of pictures in theCLVS. sps_isp_enabled_flag equal to 0 specifies that intra predictionwith subpartitions is disabled and not used in decoding of pictures inthe CLVS.sps_mrl_enabled_flag equal to 1 specifies that intra prediction withmultiple reference lines is enabled and may be used in decoding ofpictures in the CLVS. sps_mrl_enabled_flag equal to 0 specifies thatintra prediction with multiple reference lines is disabled and not usedin decoding of pictures in the CLVS.sps_mip_enabled_flag equal to 1 specifies that matrix-based intraprediction is enabled and may be used in decoding of pictures in theCLVS. sps_mip_enabled_flag equal to 0 specifies that matrix-based intraprediction is disabled and not used in decoding of pictures in the CLVS.sps_cclm_enabled_flag equal to 0 specifies that the cross-componentlinear model intra prediction from luma component to chroma component isdisabled and not used in decoding of pictures in the CLVS.sps_cclm_enabled_flag equal to 1 specifies that the cross-componentlinear model intra prediction from luma component to chroma component isenabled and may be used in decoding of pictures in the CLVS. Whensps_cclm_enabled_flag is not present, it is inferred to be equal to 0.sps_chroma_horizontal_collocated_flag equal to 1 specifies thatprediction processes operate in a manner designed for chroma samplepositions that are not horizontally shifted relative to correspondingluma sample positions. sps_chroma_horizontal_collocated_flag equal to 0specifies that prediction processes operate in a manner designed forchroma sample positions that are shifted to the right by 0.5 in units ofluma samples relative to corresponding luma sample positions. Whensps_chroma_horizontal_collocated_flag is not present, it is inferred tobe equal to 1.sps_chroma_vertical_collocated_flag equal to 1 specifies that predictionprocesses operate in a manner designed for chroma sample positions thatare not vertically shifted relative to corresponding luma samplepositions. sps_chroma_vertical_collocated_flag equal to 0 specifies thatprediction processes operate in a manner designed for chroma samplepositions that are shifted downward by 0.5 in units of luma samplesrelative to corresponding luma sample positions. Whensps_chroma_vertical_collocated_flag is not present, it is inferred to beequal to 1.sps_mts_enabled_flag equal to 1 specifies thatsps_explicit_mts_intra_enabled_flag andsps_explicit_mts_inter_enabled_flag are present in the SPS.sps_mts_enabled_flag equal to 0 specifies thatsps_explicit_mts_intra_enabled_flag andsps_explicit_mts_inter_enabled_flag are not present in the SPS.sps_explicit_mts_intra_enabled_flag equal to 1 specifies that mts_idxmay be present in the intra coding unit syntax of the CLVS.sps_explicit_mts_intra_enabled_flag equal to 0 specifies that mts_idx isnot present in the intra coding unit syntax of the CLVS. When notpresent, the value of sps_explicit_mts_intra_enabled_flag is inferred tobe equal to 0.sps_explicit_mts_inter_enabled_flag equal to 1 specifies that mts_idxmay be present in the inter coding unit syntax of the CLVS.sps_explicit_mts_inter_enabled_flag equal to 0 specifies that mts_idx isnot present in the inter coding unit syntax of the CLVS. When notpresent, the value of sps_explicit_mts_inter_enabled_flag is inferred tobe equal to 0.sps_palette_enabled_flag equal to 1 specifies that pred_mode_plt_flagmay be present in the coding unit syntax of the CLVS.sps_palette_enabled_flag equal to 0 specifies that pred_mode_plt_flag isnot present in the coding unit syntax of the CLVS. Whensps_palette_enabled_flag is not present, it is inferred to be equal to0.sps_act_enabled_flag equal to 1 specifies that adaptive colour transformis enabled and may be used in decoding of pictures in the CLVS and thecu_act_enabled_flag may be present in the coding unit syntax of theCLVS.sps_act_enabled_flag equal to 0 specifies that adaptive colour transformis disabled and not used in decoding of pictures in the CLVS andcu_act_enabled_flag is not present in the coding unit syntax of theCLVS. When sps_act_enabled_flag is not present, it is inferred to beequal to 0.sps_internal_bit_depth_minus_input_bit_depth specifies the minimumallowed quantization parameter for transform skip mode as follows:

QpPrimeTsMin=4+6*sps_internal_bit_depth_minus_input_bit_depth

The value of sps_internal_bit_depth_minus_input_bit_depth shall be inthe range of 0 to 8, inclusive.

sps_ibc_enabled_flag equal to 1 specifies that the IBC prediction modeis enabled and may be used in decoding of pictures in the CLVS.sps_ibc_enabled_flag equal to 0 specifies that the IBC prediction modeis disabled and not used in decoding of pictures in the CLVS. Whensps_ibc_enabled_flag is not present, it is inferred to be equal to 0.sps_six_minus_max_num_ibc_merge_cand, when sps_ibc_enabled_flag is equalto 1, specifies the maximum number of IBC merging block vectorprediction (BVP) candidates supported in the SPS subtracted from 6. Thevalue of sps_six_minus_max_num_ibc_merge_cand shall be in the range of 0to 5, inclusive.The maximum number of IBC merging BVP candidates, MaxNumIbcMergeCand, isderived as follows:

if(sps_ibc_enabled_flag)

-   -   MaxNumIbcMergeCand=6−sps_six_minus_max_num_ibc_merge_cand

else

-   -   MaxNumIbcMergeCand=0        sps_lmcs_enabled_flag equal to 1 specifies that luma mapping        with chroma scaling is enabled and may be used in decoding of        pictures in the CLVS. sps_lmcs_enabled_flag equal to 0 specifies        that luma mapping with chroma scaling is disabled and not used        in decoding of pictures in the CLVS.        sps_lfnst_enabled_flag equal to 1 specifies that lfnst_idx may        be present in intra coding unit syntax. sps_lfnst_enabled_flag        equal to 0 specifies that lfnst_idx is not present in intra        coding unit syntax.        sps_ladf_enabled_flag equal to 1 specifies that        sps_num_ladf_intervals_minus2,        sps_ladf_lowest_interval_qp_offset, sps_ladf_qp_offset[i], and        sps_ladf_delta_threshold_minus1[i] are present in the SPS.        sps_ladf_enabled_flag equal to 0 specifies that        sps_num_ladf_intervals_minus2,        sps_ladf_lowest_interval_qp_offset, sps_ladf_qp_offset[i], and        sps_ladf_delta_threshold_minus1[i] are not present in the SPS.        sps_num_ladf_intervals_minus2 plus 2 specifies the number of        sps_ladf_delta_threshold_minus 1[i] and sps_ladf_qp_offset[i]        syntax elements that are present in the SPS. The value of        sps_num_ladf_intervals_minus2 shall be in the range of 0 to 3,        inclusive.        sps_ladf_lowest_interval_qp_offset specifies the offset used to        derive the variable qP as specified. The value of        sps_ladf_lowest_interval_qp_offset shall be in the range of −63        to 63, inclusive.

sps_ladf_qp_offset[i] specifies the offset array used to derive thevariable qP as specified. The value of sps_ladf_qp_offset[i] shall be inthe range of −63 to 63, inclusive.

sps_ladf_delta_threshold_minus1[i] is used to compute the values ofSpsLadflntervalLowerBound[i], which specifies the lower bound of thei-th luma intensity level interval. The value ofsps_ladf_delta_threshold_minus1[i] shall be in the range of 0 to2^(BitDepth)−3, inclusive.The value of SpsLadflntervalLowerBound[0] is set equal to 0.For each value of i in the range of 0 to sps_num_ladf_intervals_minus2,inclusive, the variable SpsLadflntervalLowerBound[i+1] is derived asfollows:

-   -   SpsLadflntervalLowerBound[i+1]=SpsLadflntervalLowerBound[i]        -   +sps_ladf_delta_threshold_minus1[i]+1            sps_explicit_scaling_list_enabled_flag equal to 1 specifies            that the use of an explicit scaling list, which is signalled            in a scaling list APS, in the scaling process for transform            coefficients when decoding a slice is enabled for the CLVS.            sps_explicit_scaling_list_enabled_flag equal to 0 specifies            that the use of an explicit scaling list in the scaling            process for transform coefficients when decoding a slice is            disabled for the CLVS.            sps_scaling_matrix_for_lfnst_disabled_flag equal to 1            specifies that scaling matrices are disabled and not applied            to blocks coded with LFNST for the CLVS.            sps_scaling_matrix_for_lfnst_disabled_flag equal to 0            specifies that the scaling matrices is enabled and may be            applied to blocks coded with LFNST for the CLVS. When not            present, the value of            sps_scaling_matrix_for_lfnst_disabled_flag is inferred to be            equal to 1.            sps_scaling_matrix_for_alternative_colour_space_disabled_flag            equal to 1 specifies that for the CLVS scaling matrices are            disabled and not applied to blocks when the colour space of            the blocks is not equal to the designated colour space of            scaling matrix.            sps_scaling_matrix_for_alternative_colour_space_disabled_flag            equal to 0 specifies that for the CLVS scaling matrices are            enabled and may be applied to the blocks when the colour            space of the blocks is equal to the designated colour space            of scaling matrices. When not present, the value of            sps_scaling_matrix_for_alternative_colour_sapce_disabled_flag            is inferred to be equal to 0.            sps_scaling_matrix_designated_colour_space_flag equal to 1            specifies that the designated colour space of scaling            matrices is the original colour space.            sps_scaling_matrix_designated_colour_space_flag equal to 0            specifies that the designated colour space of scaling            matrices is the transformed colour space. When not present,            the value of sps_scaling_matrix_designated_colour_space_flag            is inferred to be equal to 1.            sps_dep_quant_enabled_flag equal to 0 specifies that            dependent quantization is disabled and not used for pictures            referring to the SPS. sps_dep_quant_enabled_flag equal to 1            specifies that dependent quantization is enabled and may be            used for pictures referring to the SPS.            sps_sign_data_hiding_enabled_flag equal to 0 specifies that            sign bit hiding is disabled and not used for pictures            referring to the SPS. sps_sign_data_hiding_enabled_flag            equal to 1 specifies that sign bit hiding is enabled and may            be used for pictures referring to the SPS. When            sps_sign_data_hiding_enabled_flag is not present, it is            inferred to be equal to 0.            sps_virtual_boundaries_enabled_flag equal to 1 specifies            that disabling in-loop filtering across virtual boundaries            is enabled and may be applied in the coded pictures in the            CLVS. sps_virtual_boundaries_enabled_flag equal to 0            specifies that disabling in-loop filtering across virtual            boundaries is disabled and not applied in the coded pictures            in the CLVS. In-loop filtering operations include the            deblocking filter, sample adaptive offset filter, and            adaptive loop filter operations.            sps_virtual_boundaries_present_flag equal to 1 specifies            that information of virtual boundaries is signalled in the            SPS. sps_virtual_boundaries_present_flag equal to 0            specifies that information of virtual boundaries is not            signalled in the SPS. When there is one or more than one            virtual boundaries signalled in the SPS, the in-loop            filtering operations are disabled across the virtual            boundaries in pictures referring to the SPS. In-loop            filtering operations include the deblocking filter, sample            adaptive offset filter, and adaptive loop filter operations.            It is a requirement of bitstream conformance that when the            value of sps_res_change_in_clvs_allowed_flag is equal to 1,            the value of sps_virtual_boundaries_present_flag shall be            equal to 0.            sps_num_ver_virtual_boundaries specifies the number of            sps_virtual_boundary_pos_x[i] syntax elements that are            present in the SPS. When sps_num_ver_virtual_boundaries is            not present, it is inferred to be equal to 0.            sps_virtual_boundary_pos_x[i] specifies the location of the            i-th vertical virtual boundary in units of luma samples            divided by 8. The value of sps_virtual_boundary_pos_x[i]            shall be in the range of 1 to            Ceil(sps_pic_width_max_in_luma_samples÷8)−1, inclusive.            sps_num_hor_virtual_boundaries specifies the number of            sps_virtual_boundary_pos_y[i] syntax elements that are            present in the SPS. When sps_num_hor_virtual_boundaries is            not present, it is inferred to be equal to 0. When            sps_virtual_boundaries_enabled_flag is equal to 1 and            sps_virtual_boundaries_present_flag is equal to 1, the sum            of sps_num_ver_virtual_boundaries and            sps_num_hor_virtual_boundaries shall be greater than 0.            sps_virtual_boundary_pos_y[i] specifies the location of the            i-th horizontal virtual boundary in units of luma samples            divided by 8. The value of sps_virtual_boundary_pos_y[i]            shall be in the range of 1 to            Ceil(sps_pic_height_max_in_luma_samples÷8)−1, inclusive.            sps_general_hrd_params_present_flag equal to 1 specifies            that the SPS contains a general_hrd_parameters( ) syntax            structure and an ols_hrd_parameters( ) syntax structure.            sps_general_hrd_params_present_flag equal to 0 specifies            that the SPS does not contain a general_hrd_parameters( )            syntax structure or an ols_hrd_parameters( ) syntax            structure.            sps_sublayer_cpb_params_present_flag equal to 1 specifies            that the ols_hrd_parameters( ) syntax structure in the SPS            includes HRD parameters for sublayer representations with            TemporalId in the range of 0 to sps_max_sublayers_minus1,            inclusive. sps_sublayer_cpb_params_present_flag equal to 0            specifies that the ols_hrd_parameters( ) syntax structure in            the SPS includes HRD parameters for the sublayer            representation with TemporalId equal to            sps_max_sublayers_minus1 only. When sps_max_sublayers_minus1            is equal to 0, the value of            sps_sublayer_cpb_params_present_flag is inferred to be equal            to 0.            When sps_sublayer_cpb_params_present_flag is equal to 0, the            HRD parameters for the sublayer representations with            TemporalId in the range of 0 to sps_max_sublayers_minus1−1,            inclusive, are inferred to be the same as that for the            sublayer representation with TemporalId equal to            sps_max_sublayers_minus1. These include the HRD parameters            starting from the fixed_pic_rate_general_flag[i] syntax            element till the sublayer_hrd_parameters(i) syntax structure            immediately under the condition            “if(general_vcl_hrd_params_present_flag)” in the            ols_hrd_parameters syntax structure.            sps_field_seq_flag equal to 1 indicates that the CLVS            conveys pictures that represent fields. sps_field_seq_flag            equal to 0 indicates that the CLVS conveys pictures that            represent frames. When general_frame_only_constraint_flag is            equal to 1, the value of sps_field_seq_flag shall be equal            to 0. When sps_field_seq_flag is equal to 1, a frame-field            information SEI message shall be present for every coded            picture in the CLVS.    -   NOTE—The specified decoding process does not treat pictures that        represent fields or frames differently. A sequence of pictures        that represent fields would therefore be coded with the picture        dimensions of an individual field. For example, pictures that        represent 1080i fields would commonly have cropped output        dimensions of 1920×540, while the sequence picture rate would        commonly express the rate of the source fields (typically        between 50 and 60 Hz), instead of the source frame rate        (typically between 25 and 30 Hz).        sps_vui_parameters_present_flag equal to 1 specifies that the        syntax structure vui_parameters( ) is present in the SPS RBSP        syntax structure. sps_vui_parameters_present_flag equal to 0        specifies that the syntax structure vui_parameters( ) is not        present in the SPS RBSP syntax structure.        sps_extension_flag equal to 0 specifies that no        sps_extension_data_flag syntax elements are present in the SPS        RB SP syntax structure. sps_extension_flag equal to 1 specifies        that there are sps_extension_data_flag syntax elements present        in the SPS RBSP syntax structure.        sps_extension_data_flag may have any value. Its presence and        value do not affect decoder conformance to profiles specified in        this version of this Specification. Decoders conforming to this        version of this Specification shall ignore all        sps_extension_data_flag syntax elements.

As provided in Table 2, a NAL unit may include adecoding_capability_information (DCI) syntax structure. Table 5illustrates the syntax structure of the decoding capability informationprovided in JVET-R2001.

TABLE 5 Descriptor decoding_capability_information_rbsp( ) {dci_reserved_zero_4bits u(4) dci_num_ptls_minus1 u(4) for( i = 0; i <=dci_num_ptls_minus1; i++ ) profile_tier_level( 1, 0 ) dci_extension_flagu(1) if( dci_extension_flag ) while( more_rbsp_data( ) )dci_extension_data_flag u(1) rbsp_trailing_bits( ) }

With respect to Table 5, JVET-R2001 provides the following semantics:

A DCI RBSP may be made available to the decoder, through either beingpresent in the bitstream, included in at least the first AU of thebitstream, or provided through external means.

-   -   NOTE—The information contained in the DCI RB SP is not necessary        for operation of the decoding process specified in this        Specification.        When present, all DCI NAL units in a bitstream shall have the        same content.        dci_reserved_zero_4 bits shall be equal to 0 in bitstreams        conforming to this version of this Specification. The values        greater than 0 for dci_reserved_zero_4 bits are reserved for        future use by ITU-T|ISO/IEC.        dci_num_ptls_minus1 plus 1 specifies the number of        profile_tier_level( ) syntax structures in the DCI NAL unit. The        value of dci_num_ptls_minus1 shall be in the range of 0 to 14,        inclusive. The value 15 for dci_num_ptls_minus1 is reserved for        future use by ITU-T|ISO/IEC.        It is a requirement of bitstream conformance that each OLS in a        CVS in the bitstream shall conforms to at least one of the        profile_tier_level( ) syntax structures in the DCI NAL unit.    -   NOTE—The DCI NAL unit may include PTL information, possibly        carried in multiple profile_tier_level( ) syntax structures,        that applies collectively to multiple OLSs, and does not need to        include PTL information for each of the OLSs individually.        dci_extension_flag equal to 0 specifies that no        dci_extension_data_flag syntax elements are present in the DCI        RBSP syntax structure. dci_extension_flag equal to 1 specifies        that there are dci_extension_data_flag syntax elements present        in the DCI RBSP syntax structure.        dci_extension_data_flag may have any value. Its presence and        value do not affect decoder conformance to profiles specified.        Decoders conforming to this version of this Specification shall        ignore all dci_extension_data_flag syntax elements.

As provided in Table 3, Table 4, and Table 5 a VPS, a SPS, and a DCI mayinclude a profile_tier_level( ) syntax structure. Table 6 illustratesthe profile_tier_level( ) syntax structure provided in JVET-R2001.

TABLE 6 Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { if( profileTierPresentFlag ) {general_profile_idc u(7) general_tier_flag u(1) general_constraint_info() } general_level_idc u(8) if( profileTierPresentFlag ) {ptl_num_sub_profiles u(8) for( i = 0; i < num_sub_profiles; i++ )general_sub_profile_idc[ i ]  u(32) } for( i = 0; i <maxNumSubLayersMinus1; i++ ) ptl_sublayer_level_present_flag[ i ] u(1)while( !byte_aligned( ) ) ptl_alignment_zero_bit  f(1) for( i = 0; i <maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

With respect to Table 6, JVET-R2001 provides the following semantics:

A profile_tier_level( ) syntax structure provides level information and,optionally, profile, tier, sub-profile, and general constraintsinformation.

When the profile_tier_level( ) syntax structure is included in a VPS,the OlsInScope is one or more OLSs specified by the VPS. When theprofile_tier_level( ) syntax structure is included in an SPS, theOlsInScope is the OLS that includes only the layer that is the lowestlayer among the layers that refer to the SPS, and this lowest layer isan independent layer.general_profile_idc indicates a profile to which OlsInScope conforms asspecified. Bitstreams shall not contain values of general_profile_idcother than those specified. Other values of general_profile_idc arereserved for future use by ITU-T|ISO/IEC.general_tier_flag specifies the tier context for the interpretation ofgeneral_level_idc as specified.general_level_idc indicates a level to which OlsInScope conforms asspecified. Bitstreams shall not contain values of general_level_idcother than those specified. Other values of general_level_idc arereserved for future use by ITU-T|ISO/IEC.

-   -   NOTE—A greater value of general_level_idc indicates a higher        level. The maximum level signalled in the DCI NAL unit for        OlsInScope may be higher than but cannot be lower than the level        signalled in the SPS for a CLVS contained within OlsInScope.    -   NOTE—When OlsInScope conforms to multiple profiles,        general_profile_idc should indicate the profile that provides        the preferred decoded result or the preferred bitstream        identification, as determined by the encoder (in a manner not        specified in this Specification).    -   NOTE—When the CVSs of OlsInScope conform to different profiles,        multiple profile_tier_level( )) syntax structures may be        included in the DCI NAL unit such that for each CVS of the        OlsInScope there is at least one set of indicated profile, tier,        and level for a decoder that is capable of decoding the CVS.        ptl_num_sub_profiles specifies the number of the        general_sub_profile_idc[i] syntax elements.        general_sub_profile_idc[i] indicates the i-th interoperability        metadata registered as specified by Rec. ITU-T T.35, the        contents of which are not specified in this Specification.        ptl_sublayer_level_present_flag[i] equal to 1 specifies that        level information is present in the profile_tier_level( ) syntax        structure for the sublayer representation with TemporalId equal        to i. sublayer_level_present_flag[i] equal to 0 specifies that        level information is not present in the profile_tier_level( )        syntax structure for the sublayer representation with TemporalId        equal to i.        ptl_alignment_zero_bits shall be equal to 0.        The semantics of the syntax element sublayer_level_idc[i] is,        apart from the specification of the inference of not present        values, the same as the syntax element general_level_idc, but        apply to the sublayer representation with TemporalId equal to i.        When not present, the value of sublayer_level_idc[i] is inferred        as follows:    -   sublayer_level_idc[maxNumSubLayersMinus1] is inferred to be        equal to general_level_idc of the same profile_tier_level( )        structure,    -   For i from maxNumSubLayersMinus1−1 to 0 (in decreasing order of        values of i), inclusive, sublayer_level_idc[i] is inferred to be        equal to sublayer_level_idc[i+1].

As provided in Table 6, a profile_tier_level( ) syntax structure mayinclude includes general_constraint_info( ) syntax structure. Table 7illustrates the general_constraint_info( ) syntax structure provided inJVET-R2001

TABLE 7 Descriptor general_constraint_info( ) {general_non_packed_constraint_flag u(1)general_frame_only_constraint_flag u(1)general_non_projected_constraint_flag u(1)general_one_picture_only_constraint_flag u(1) intra_only_constraint_flagu(1) max_bitdepth_constraint_idc u(4) max_chroma_format_constraint_idcu(2) single_layer_constraint_flag u(1)all_layers_independent_constraint_flag u(1)no_ref_pic_resampling_constraint_flag u(1)no_res_change_in_clvs_constraint_flag u(1)one_tile_per_pic_constraint_flag u(1)pic_header_in_slice_header_constraint_flag u(1)one_slice_per_pic_constraint_flag u(1)one_subpic_per_pic_constraint_flag u(1)no_qtbtt_dual_tree_intra_constraint_flag u(1)no_partition_constraints_override_constraint_flag u(1)no_sao_constraint_flag u(1) no_alf_constraint_flag u(1)no_ccalf_constraint_flag u(1) no_joint_cbcr_constraint_flag u(1)no_mrl_constraint_flag u(1) no_isp_constraint_flag u(1)no_mip_constraint_flag u(1) no_ref_wraparound_constraint_flag u(1)no_temporal_mvp_constraint_flag u(1) no_sbtmvp_constraint_flag u(1)no_amvr_constraint_flag u(1) no_bdof_constraint_flag u(1)no_dmvr_constraint_flag u(1) no_cclm_constraint_flag u(1)no_mts_constraint_flag u(1) no_sbt_constraint_flag u(1)no_lfnst_constraint_flag u(1) no_affine_motion_constraint_flag u(1)no_mmvd_constraint_flag u(1) no_smvd_constraint_flag u(1)no_prof_constraint_flag u(1) no_bcw_constraint_flag u(1)no_ibc_constraint_flag u(1) no_ciip_constraint_flag u(1)no_gpm_constraint_flag u(1) no_ladf_constraint_flag u(1)no_transform_skip_constraint_flag u(1) no_bdpcm_constraint_flag u(1)no_palette_constraint_flag u(1) no_act_constraint_flag u(1)no_lmcs_constraint_flag u(1) no_cu_qp_delta_constraint_flag u(1)no_chroma_qp_offset_constraint_flag u(1) no_dep_quant_constraint_flagu(1) no_sign_data_hiding_constraint_flag u(1) no_tsrc_constraint_flagu(1) no_mixed_nalu_types_in_pic_constraint_flag u(1)no_trail_constraint_flag u(1) no_stsa_constraint_flag u(1)no_rasl_constraint_flag u(1) no_radl_constraint_flag u(1)no_idr_constraint_flag u(1) no_cra_constraint_flag u(1)no_gdr_constraint_flag u(1) no_aps_constraint_flag u(1) while(!byte_aligned( ) ) gci_alignment_zero_bit  f(1) gci_num_reserved_bytesu(8) for( i = 0; i < gci_num_reserved_bytes; i++ ) gci_reserved_byte[ i] u(8) }

With respect to Table 7, JVET-R2001 provides the following semantics:

general_non_packed_constraint_flag equal to 1 specifies that there shallnot be any frame packing arrangement SEI messages present in thebitstream of the OlsInScope. general_non_packed_constraint_flag equal to0 does not impose such a constraint.

-   -   NOTE—Decoders may ignore the value of        general_non_packed_constraint_flag, as there are no decoding        process requirements associated with the presence or        interpretation of frame packing arrangement SEI messages.        general_frame_only_constraint_flag equal to 1 specifies that        OlsInScope conveys pictures that represent frames.        general_frame_only_constraint_flag equal to 0 specifies that        OlsInScope conveys pictures that may or may not represent        frames.    -   NOTE—Decoders may ignore the value of        general_frame_only_constraint_flag, as there are no decoding        process requirements associated with it.        general_non_projected_constraint_flag equal to 1 specifies that        there shall not be any equirectangular projection SEI messages        or generalized cubemap projection SEI messages present in the        bitstream of the OlsInScope.        general_non_projected_constraint_flag equal to 0 does not impose        such a constraint.    -   NOTE—Decoders may ignore the value of        general_non_projected_constraint_flag, as there are no decoding        process requirements associated with the presence or        interpretation of equirectangular projection SEI messages and        generalized cubemap projection SEI messages.        general_one_picture_only_constraint_flag equal to 1 specifies        that there is only one coded picture in the bitstream.        general_one_picture_only_constraint_flag equal to 0 does not        impose such a constraint.        intra_only_constraint_flag equal to 1 specifies that        sh_slice_type shall be equal to I. intra_only_constraint_flag        equal to 0 does not impose such a constraint. When        general_one_picture_only_constraint_flag is equal to 1, the        value of intra_only_constraint_flag shall be equal to 1.        max_bitdepth_constraint_idc specifies that sps_bit_depth_minus8        shall be in the range of 0 to max_bitdepth_constraint_idc,        inclusive.        max_chroma_format_constraint_idc specifies that        sps_chroma_format_idc shall be in the range of 0 to        max_chroma_format_constraint_idc, inclusive.        single_layer_constraint_flag equal to 1 specifies that        sps_video_parameter_set_id shall be equal to 0.        single_layer_constraint_flag equal to 0 does not impose such a        constraint. When general_one_picture_only_constraint_flag is        equal to 1, the value of single_layer_constraint_flag shall be        equal to 1.        all_layers_independent_constraint_flag equal to 1 specifies that        vps_all_independent_layers_flag shall be equal to 1.        all_layers_independent_constraint_flag equal to 0 does not        impose such a constraint.        no_ref_pic_resampling_constraint_flag equal to 1 specifies that        sps_ref_pic_resampling_enabled_flag shall be equal to 0.        no_ref_pic_resampling_constraint_flag equal to 0 does not impose        such a constraint.        no_res_change_in_clvs_constraint_flag equal to 1 specifies that        sps_res_change_in_clvs_allowed_flag shall be equal to 0.        no_res_change_in_clvs_constraint_flag equal to 0 does not impose        such a constraint.        one_tile_per_pic_constraint_flag equal to 1 specifies that each        picture shall contain only one tile.        one_tile_per_pic_constraint_flag equal to 0 does not impose such        a constraint.        pic_header_in_slice_header_constraint_flag equal to 1 specifies        that each picture shall contain only one slice and the value of        sh_picture_header_in_slice_header_flag in each slice shall be        equal to 1. pic_header_in_slice_header_constraint_flag equal to        0 does not impose such a constraint.        one_slice_per_pic_constraint_flag equal to 1 specifies that each        picture shall contain only one slice.        one_slice_per_pic_constraint_flag equal to 0 does not impose        such a constraint. When        pic_header_in_slice_header_constraint_flag is equal to 1, the        value of one_slice_per_pic_constraint_flag shall be equal to 1.        one_subpic_per_pic_constraint_flag equal to 1 specifies that        each picture shall contain only one subpicture.        one_subpic_per_pic_constraint_flag equal to 0 does not impose        such a constraint. When one_slice_per_pic_constraint_flag is        equal to 1, the value of one_subpic_per_pic_constraint_flag        shall be equal to 1.        no_qtbtt_dual_tree_intra_constraint_flag equal to 1 specifies        that sps_qtbtt_dual_tree_intra_flag shall be equal to 0.        no_qtbtt_dual_tree_intra_constraint_flag equal to 0 does not        impose such a constraint. When max_chroma_format_constraint_idc        is equal to 0, the value of        no_qtbtt_dual_tree_intra_constraint_flag shall be equal to 1.        no_partition_constraints_override_constraint_flag equal to 1        specifies that sps_partition_constraints_override_enabled_flag        shall be equal to 0.        no_partition_constraints_override_constraint_flag equal to 0        does not impose such a constraint.        no_sao_constraint_flag equal to 1 specifies that        sps_sao_enabled_flag shall be equal to 0. no_sao_constraint_flag        equal to 0 does not impose such a constraint.        no_alf_constraint_flag equal to 1 specifies that        sps_alf_enabled_flag shall be equal to 0. no_alf_constraint_flag        equal to 0 does not impose such a constraint.        no_ccalf_constraint_flag equal to 1 specifies that        sps_ccalf_enabled_flag shall be equal to 0.        no_ccalf_constraint_flag equal to 0 does not impose such a        constraint. When max_chroma_format_constraint_idc is equal to 0        or no_alf_constraint_flag is equal 1, the value of        no_ccalf_constraint_flag shall be equal to 1.        no_joint_cbcr_constraint_flag equal to 1 specifies that        sps_joint_cbcr_enabled_flag shall be equal to 0.        no_joint_cbcr_constraint_flag equal to 0 does not impose such a        constraint. When max_chroma_format_constraint_idc is equal to 0,        the value of no_joint_cbcr_constraint_flag shall be equal to 1.        no_mrl_constraint_flag equal to 1 specifies that        sps_mrl_enabled_flag shall be equal to 0. no_mrl_constraint_flag        equal to 0 does not impose such a constraint.        no_isp_constraint_flag equal to 1 specifies that        sps_isp_enabled_flag shall be equal to 0. no_isp_constraint_flag        equal to 0 does not impose such a constraint.        no_mip_constraint_flag equal to 1 specifies that        sps_mip_enabled_flag shall be equal to 0. no_mip_constraint_flag        equal to 0 does not impose such a constraint.        no_ref_wraparound_constraint_flag equal to 1 specifies that        sps_ref_wraparound_enabled_flag shall be equal to 0.        no_ref_wraparound_constraint_flag equal to 0 does not impose        such a constraint. When intra_only_constraint_flag is equal to        1, the value of no_ref_wraparound_constraint_flag shall be equal        to 1.        no_temporal_mvp_constraint_flag equal to 1 specifies that        sps_temporal_mvp_enabled_flag shall be equal to 0.        no_temporal_mvp_constraint_flag equal to 0 does not impose such        a constraint. When intra_only_constraint_flag is equal to 1, the        value of no_temporal_mvp_constraint_flag shall be equal to 1.        no_sbtmvp_constraint_flag equal to 1 specifies that        sps_sbtmvp_enabled_flag shall be equal to 0.        no_sbtmvp_constraint_flag equal to 0 does not impose such a        constraint. When no_temporal_mvp_constraint_flag is equal to 1,        the value of no_sbtmvp_constraint_flag shall be equal to 1.        no_amvr_constraint_flag equal to 1 specifies that        sps_amvr_enabled_flag shall be equal to 0.        no_amvr_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_amvr_constraint_flag shall be equal to 1.        no_bdof_constraint_flag equal to 1 specifies that        sps_bdof_enabled_flag shall be equal to 0.        no_bdof_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_bdof_constraint_flag shall be equal to 1.        no_dmvr_constraint_flag equal to 1 specifies that        sps_dmvr_enabled_flag shall be equal to 0.        no_dmvr_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_dmvr_constraint_flag shall be equal to 1.        no_cclm_constraint_flag equal to 1 specifies that        sps_cclm_enabled_flag shall be equal to 0.        no_cclm_constraint_flag equal to 0 does not impose such a        constraint. When max_chroma_format_constraint_idc is equal to 0,        the value of no_cclm_constraint_flag shall be equal to 1.        no_mts_constraint_flag equal to 1 specifies that        sps_mts_enabled_flag shall be equal to 0. no_mts_constraint_flag        equal to 0 does not impose such a constraint.        no_sbt_constraint_flag equal to 1 specifies that        sps_sbt_enabled_flag shall be equal to 0. no_sbt_constraint_flag        equal to 0 does not impose such a constraint.        no_lfnst_constraint_flag equal to 1 specifies that        sps_lfnst_enabled_flag shall be equal to 0.        no_lfnst_constraint_flag equal to 0 does not impose such a        constraint.        no_affine_motion_constraint_flag equal to 1 specifies that        sps_affine_enabled_flag shall be equal to 0.        no_affine_motion_constraint_flag equal to 0 does not impose such        a constraint. When intra_only_constraint_flag is equal to 1, the        value of no_affine_motion_constraint_flag shall be equal to 1.        no_mmvd_constraint_flag equal to 1 specifies that        sps_mmvd_enabled_flag shall be equal to 0.        no_mmvd_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_mmvd_constraint_flag shall be equal to 1.        no_smvd_constraint_flag equal to 1 specifies that        sps_smvd_enabled_flag shall be equal to 0.        no_smvd_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_smvd_constraint_flag shall be equal to 1.        no_prof_constraint_flag equal to 1 specifies that        sps_affine_prof_enabled_flag shall be equal to 0.        no_prof_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_prof_constraint_flag shall be equal to 1.        no_bcw_constraint_flag equal to 1 specifies that        sps_bcw_enabled_flag shall be equal to 0. no_bcw_constraint_flag        equal to 0 does not impose such a constraint. When        intra_only_constraint_flag is equal to 1, the value of        no_bcw_constraint_flag shall be equal to 1.        no_ibc_constraint_flag equal to 1 specifies that        sps_ibc_enabled_flag shall be equal to 0. no_ibc_constraint_flag        equal to 0 does not impose such a constraint.        no_ciip_constraint_flag equal to 1 specifies that        sps_ciip_enabled_flag shall be equal to 0.        no_cipp_constraint_flag equal to 0 does not impose such a        constraint. When intra_only_constraint_flag is equal to 1, the        value of no_cipp_constraint_flag shall be equal to 1.        no_gpm_constraint_flag equal to 1 specifies that        sps_gpm_enabled_flag shall be equal to 0. no_gpm_constraint_flag        equal to 0 does not impose such a constraint. When        intra_only_constraint_flag is equal to 1, the value of        no_gpm_constraint_flag shall be equal to 1.        no_ladf_constraint_flag equal to 1 specifies that        sps_ladf_enabled_flag shall be equal to 0.        no_ladf_constraint_flag equal to 0 does not impose such a        constraint.        no_transform_skip_constraint_flag equal to 1 specifies that        sps_transform_skip_enabled_flag shall be equal to 0.        no_transform_skip_constraint_flag equal to 0 does not impose        such a constraint.        no_bdpcm_constraint_flag equal to 1 specifies that        sps_bdpcm_enabled_flag shall be equal to 0.        no_bdpcm_constraint_flag equal to 0 does not impose such a        constraint.        no_palette_constraint_flag equal to 1 specifies that        sps_palette_enabled_flag shall be equal to 0.        no_palette_constraint_flag equal to 0 does not impose such a        constraint.        no_act_constraint_flag equal to 1 specifies that        sps_act_enabled_flag shall be equal to 0. no_act_constraint_flag        equal to 0 does not impose such a constraint.        no_lmcs_constraint_flag equal to 1 specifies that        sps_lmcs_enabled_flag shall be equal to 0.        no_lmcs_constraint_flag equal to 0 does not impose such a        constraint.        no_cu_qp_delta_constraint_flag equal to 1 specifies that        pps_cu_qp_delta_enabled_flag shall be equal to 0.        no_cu_qp_delta_constraint_flag equal to 0 does not impose such a        constraint.        no_chroma_qp_offset_constraint_flag equal to 1 specifies that        pps_cu_chroma_qp_offset_list_enabled_flag shall be equal to 0.        no_chroma_qp_offset_constraint_flag equal to 0 does not impose        such a constraint.        no_dep_quant_constraint_flag equal to 1 specifies that        sps_dep_quant_enabled_flag shall be equal to 0.        no_dep_quant_constraint_flag equal to 0 does not impose such a        constraint.        no_sign_data_hiding_constraint_flag equal to 1 specifies that        sps_sign_data_hiding_enabled_flag shall be equal to 0.        no_sign_data_hiding_constraint_flag equal to 0 does not impose        such a constraint.        no_tsrc_constraint_flag equal to 1 specifies that        sh_ts_residual_coding_disabled_flag shall be equal to 0.        no_tsrc_constraint_flag equal to 0 does not impose such a        constraint.        no_mixed_nalu_types_in_pic_constraint_flag equal to 1 specifies        that it is a requirement of bitstream conformance that        pps_mixed_nalu_types_in_pic_flag shall be equal to 0.        no_mixed_nalu_types_in_pic_constraint_flag equal to 0 does not        impose such a constraint.        no_trail_constraint_flag equal to 1 specifies that there shall        be no NAL unit with nuh_unit_type equal to TRAIL_NUT present in        OlsInScope. no_trail_constraint_flag equal to 0 does not impose        such a constraint.        no_stsa_constraint_flag equal to 1 specifies that there shall be        no NAL unit with nuh_unit_type equal to STSA_NUT present in        OlsInScope. no_stsa_constraint_flag equal to 0 does not impose        such a constraint.        no_rasl_constraint_flag equal to 1 specifies that there shall be        no NAL unit with nuh_unit_type equal to RASL_NUT present in        OlsInScope. no_rasl_constraint_flag equal to 0 does not impose        such a constraint.        no_radl_constraint_flag equal to 1 specifies that there shall be        no NAL unit with nuh_unit_type equal to RADL_NUT present in        OlsInScope. no_radl_constraint_flag equal to 0 does not impose        such a constraint.        no_idr_constraint_flag equal to 1 specifies that there shall be        no NAL unit with nuh_unit_type equal to IDR_W_RADL or IDR_N_LP        present in OlsInScope. no_idr_constraint_flag equal to 0 does        not impose such a constraint.        no_cra_constraint_flag equal to 1 specifies that there shall be        no NAL unit with nuh_unit_type equal to CRA_NUT present in        OlsInScope. no_cra_constraint_flag equal to 0 does not impose        such a constraint.        no_gdr_constraint_flag equal to 1 specifies that        sps_gdr_enabled_flag shall be equal to 0. no_gdr_constraint_flag        equal to 0 does not impose such a constraint.        no_aps_constraint_flag equal to 1 specifies that there shall be        no NAL unit with nuh_unit_type equal to PREFIX_APS_NUT or        SUFFIX_APS_NUT present in OlsInScope, and the        sps_lmcs_enabled_flag and sps_scaling_list_enabled_flag shall        both be equal to 0. no_aps_constraint_flag equal to 0 does not        impose such a constraint.        gci_alignment_zero_bits shall be equal to 0.        gci_num_reserved_bytes specifies the number of the reserved        constraint bytes. The value of gci_num_reserved_bytes shall        be 0. Other values of gci_num_reserved_bytes are reserved for        future use by ITU-T|ISO/IEC and shall not be present in        bitstreams conforming to this version of this Specification.        gci_reserved_byte[i] may have any value. Its presence and value        do not affect decoder conformance to profiles specified in this        version of this Specification. Decoders conforming to this        version of this Specification shall ignore the values of all the        gci_reserved_byte[i] syntax elements.        With respect to Table 6 and Table 7, it should be noted that the        profile_tier_level( ) syntax structure is based on constraint        flags being fixed length fields and fixed-length coded syntax        elements without conditional presence being at the beginning of        the profile_tier_level( ). That is, general_constraint_info( )        initially included fixed-length coded syntax elements without        conditional presence. However, an extension mechanism was added        to general_constraint_info( ), i.e., gci_reserved_byte[i], to        allow future versions of VVC to introduce new constraint flags.        Thus, according to JVET-R2001 in order to parse to the syntax        element general_level_idc, i.e., the syntax element immediately        subsequent to general_constraint_info( ), in a manner that is        futureproof, the value of gci_num_reserved_bytes must be        examined in order to determine how many gci_reserved_byte[i]        bytes to parse through or jump over. Thus, the        profile_tier_level( ) syntax structure and        general_constraint_info( ) provided in JVET-R2001 is less than        ideal.

It should be noted that when the PTL syntax structure is present in oneof an SPS or in a DCI, then profileTierPresentFlag is equal to 1,meaning that syntax elements with conditional presence based on thevalue of profileTierPresentFlag will always be present when theprofile_tier_level( ) syntax structure is present in an SPS and in aDCI. Furthermore, in the SPS, all syntax elements that precede theprofile_tier_level( ) syntax structure are fixed length code and alwayspresent (no conditional presence).

It should be noted that it is common for system layer applications,analyzers, and network elements to inspect the values of syntax elementsgeneral_profile_idc, general_tier_flag, and general_level_idc. Accordingto the syntax provided in Table 4 and Table 6, in JVET-R2001, in thecase where profile_tier_level( ) in the seq_parameter_set_rbsp( )inspecting the values of syntax elements general_profile_idc andgeneral_tier_flag requires parsing the 3rd byte ofseq_parameter_set_rbsp( ) However, because the location ofgeneral_level_idc in profile_tier_level( ) is based on the number ofgci_num_reserved_bytes, inspecting the values of syntax element requiresparsing the 14th byte of seq_parameter_set_rbsp( ) in the case wheregci_num_reserved_bytes is equal to 0, which would be the case forJVET-R2001. However, general_level_idc could be located at another byteposition in a future version of VVC.

According to the techniques described herein, general_constraint_info( )may be repositioned within profile_tier_level( ) and/or modified toensure syntax elements can be parsed without parsing variable lengthand/or conditionally presence syntax elements.

FIG. 1 is a block diagram illustrating an example of a system that maybe configured to code (i.e., encode and/or decode) video data accordingto one or more techniques of this disclosure. System 100 represents anexample of a system that may encapsulate video data according to one ormore techniques of this disclosure. As illustrated in FIG. 1 , system100 includes source device 102, communications medium 110, anddestination device 120. In the example illustrated in FIG. 1 , sourcedevice 102 may include any device configured to encode video data andtransmit encoded video data to communications medium 110. Destinationdevice 120 may include any device configured to receive encoded videodata via communications medium 110 and to decode encoded video data.Source device 102 and/or destination device 120 may include computingdevices equipped for wired and/or wireless communications and mayinclude, for example, set top boxes, digital video recorders,televisions, desktop, laptop or tablet computers, gaming consoles,medical imagining devices, and mobile devices, including, for example,smartphones, cellular telephones, personal gaming devices.

Communications medium 110 may include any combination of wireless andwired communication media, and/or storage devices. Communications medium110 may include coaxial cables, fiber optic cables, twisted pair cables,wireless transmitters and receivers, routers, switches, repeaters, basestations, or any other equipment that may be useful to facilitatecommunications between various devices and sites. Communications medium110 may include one or more networks. For example, communications medium110 may include a network configured to enable access to the World WideWeb, for example, the Internet. A network may operate according to acombination of one or more telecommunication protocols.Telecommunications protocols may include proprietary aspects and/or mayinclude standardized telecommunication protocols. Examples ofstandardized telecommunications protocols include Digital VideoBroadcasting (DVB) standards, Advanced Television Systems Committee(ATSC) standards, Integrated Services Digital Broadcasting (ISDB)standards, Data Over Cable Service Interface Specification (DOCSIS)standards, Global System Mobile Communications (GSM) standards, codedivision multiple access (CDMA) standards, 3rd Generation PartnershipProject (3GPP) standards, European Telecommunications StandardsInstitute (ETSI) standards, Internet Protocol (IP) standards, WirelessApplication Protocol (WAP) standards, and Institute of Electrical andElectronics Engineers (IEEE) standards.

Storage devices may include any type of device or storage medium capableof storing data. A storage medium may include a tangible ornon-transitory computer-readable media. A computer readable medium mayinclude optical discs, flash memory, magnetic memory, or any othersuitable digital storage media. In some examples, a memory device orportions thereof may be described as non-volatile memory and in otherexamples portions of memory devices may be described as volatile memory.Examples of volatile memories may include random access memories (RAM),dynamic random access memories (DRAM), and static random access memories(SRAM). Examples of non-volatile memories may include magnetic harddiscs, optical discs, floppy discs, flash memories, or forms ofelectrically programmable memories (EPROM) or electrically erasable andprogrammable (EEPROM) memories. Storage device(s) may include memorycards (e.g., a Secure Digital (SD) memory card), internal/external harddisk drives, and/or internal/external solid state drives. Data may bestored on a storage device according to a defined file format.

FIG. 4 is a conceptual drawing illustrating an example of componentsthat may be included in an implementation of system 100. In the exampleimplementation illustrated in FIG. 4 , system 100 includes one or morecomputing devices 402A-402N, television service network 404, televisionservice provider site 406, wide area network 408, local area network410, and one or more content provider sites 412A-412N. Theimplementation illustrated in FIG. 4 represents an example of a systemthat may be configured to allow digital media content, such as, forexample, a movie, a live sporting event, etc., and data and applicationsand media presentations associated therewith to be distributed to andaccessed by a plurality of computing devices, such as computing devices402A-402N. In the example illustrated in FIG. 4 , computing devices402A-402N may include any device configured to receive data from one ormore of television service network 404, wide area network 408, and/orlocal area network 410. For example, computing devices 402A-402N may beequipped for wired and/or wireless communications and may be configuredto receive services through one or more data channels and may includetelevisions, including so-called smart televisions, set top boxes, anddigital video recorders. Further, computing devices 402A-402N mayinclude desktop, laptop, or tablet computers, gaming consoles, mobiledevices, including, for example, “smart” phones, cellular telephones,and personal gaming devices.

Television service network 404 is an example of a network configured toenable digital media content, which may include television services, tobe distributed. For example, television service network 404 may includepublic over-the-air television networks, public or subscription-basedsatellite television service provider networks, and public orsubscription-based cable television provider networks and/or over thetop or Internet service providers. It should be noted that although insome examples television service network 404 may primarily be used toenable television services to be provided, television service network404 may also enable other types of data and services to be providedaccording to any combination of the telecommunication protocolsdescribed herein. Further, it should be noted that in some examples,television service network 404 may enable two-way communications betweentelevision service provider site 406 and one or more of computingdevices 402A-402N. Television service network 404 may comprise anycombination of wireless and/or wired communication media. Televisionservice network 404 may include coaxial cables, fiber optic cables,twisted pair cables, wireless transmitters and receivers, routers,switches, repeaters, base stations, or any other equipment that may beuseful to facilitate communications between various devices and sites.Television service network 404 may operate according to a combination ofone or more telecommunication protocols. Telecommunications protocolsmay include proprietary aspects and/or may include standardizedtelecommunication protocols. Examples of standardized telecommunicationsprotocols include DVB standards, ATSC standards, ISDB standards, DTMBstandards, DMB standards, Data Over Cable Service InterfaceSpecification (DOCSIS) standards, HbbTV standards, W3C standards, andUPnP standards.

Referring again to FIG. 4 , television service provider site 406 may beconfigured to distribute television service via television servicenetwork 404. For example, television service provider site 406 mayinclude one or more broadcast stations, a cable television provider, ora satellite television provider, or an Internet-based televisionprovider. For example, television service provider site 406 may beconfigured to receive a transmission including television programmingthrough a satellite uplink/downlink. Further, as illustrated in FIG. 4 ,television service provider site 406 may be in communication with widearea network 408 and may be configured to receive data from contentprovider sites 412A-412N. It should be noted that in some examples,television service provider site 406 may include a television studio andcontent may originate therefrom.

Wide area network 408 may include a packet based network and operateaccording to a combination of one or more telecommunication protocols.Telecommunications protocols may include proprietary aspects and/or mayinclude standardized telecommunication protocols. Examples ofstandardized telecommunications protocols include Global System MobileCommunications (GSM) standards, code division multiple access (CDMA)standards, 3rd Generation Partnership Project (3GPP) standards, EuropeanTelecommunications Standards Institute (ETSI) standards, Europeanstandards (EN), IP standards, Wireless Application Protocol (WAP)standards, and Institute of Electrical and Electronics Engineers (IEEE)standards, such as, for example, one or more of the IEEE 802 standards(e.g., Wi-Fi). Wide area network 408 may comprise any combination ofwireless and/or wired communication media. Wide area network 408 mayinclude coaxial cables, fiber optic cables, twisted pair cables,Ethernet cables, wireless transmitters and receivers, routers, switches,repeaters, base stations, or any other equipment that may be useful tofacilitate communications between various devices and sites. In oneexample, wide area network 408 may include the Internet. Local areanetwork 410 may include a packet based network and operate according toa combination of one or more telecommunication protocols. Local areanetwork 410 may be distinguished from wide area network 408 based onlevels of access and/or physical infrastructure. For example, local areanetwork 410 may include a secure home network.

Referring again to FIG. 4 , content provider sites 412A-412N representexamples of sites that may provide multimedia content to televisionservice provider site 406 and/or computing devices 402A-402N. Forexample, a content provider site may include a studio having one or morestudio content servers configured to provide multimedia files and/orstreams to television service provider site 406. In one example, contentprovider sites 412A-412N may be configured to provide multimedia contentusing the IP suite. For example, a content provider site may beconfigured to provide multimedia content to a receiver device accordingto Real Time Streaming Protocol (RTSP), HTTP, or the like. Further,content provider sites 412A-412N may be configured to provide data,including hypertext based content, and the like, to one or more ofreceiver devices computing devices 402A-402N and/or television serviceprovider site 406 through wide area network 408. Content provider sites412A-412N may include one or more web servers. Data provided by dataprovider site 412A-412N may be defined according to data formats.

Referring again to FIG. 1 , source device 102 includes video source 104,video encoder 106, data encapsulator 107, and interface 108. Videosource 104 may include any device configured to capture and/or storevideo data. For example, video source 104 may include a video camera anda storage device operably coupled thereto. Video encoder 106 may includeany device configured to receive video data and generate a compliantbitstream representing the video data. A compliant bitstream may referto a bitstream that a video decoder can receive and reproduce video datatherefrom. Aspects of a compliant bitstream may be defined according toa video coding standard. When generating a compliant bitstream videoencoder 106 may compress video data. Compression may be lossy(discernible or indiscernible to a viewer) or lossless. FIG. 5 is ablock diagram illustrating an example of video encoder 500 that mayimplement the techniques for encoding video data described herein. Itshould be noted that although example video encoder 500 is illustratedas having distinct functional blocks, such an illustration is fordescriptive purposes and does not limit video encoder 500 and/orsub-components thereof to a particular hardware or softwarearchitecture. Functions of video encoder 500 may be realized using anycombination of hardware, firmware, and/or software implementations.

Video encoder 500 may perform intra prediction coding and interprediction coding of picture areas, and, as such, may be referred to asa hybrid video encoder. In the example illustrated in FIG. 5 , videoencoder 500 receives source video blocks. In some examples, source videoblocks may include areas of picture that has been divided according to acoding structure. For example, source video data may includemacroblocks, CTUs, CBs, sub-divisions thereof, and/or another equivalentcoding unit. In some examples, video encoder 500 may be configured toperform additional sub-divisions of source video blocks. It should benoted that the techniques described herein are generally applicable tovideo coding, regardless of how source video data is partitioned priorto and/or during encoding. In the example illustrated in FIG. 5 , videoencoder 500 includes summer 502, transform coefficient generator 504,coefficient quantization unit 506, inverse quantization and transformcoefficient processing unit 508, summer 510, intra prediction processingunit 512, inter prediction processing unit 514, filter unit 516, andentropy encoding unit 518. As illustrated in FIG. 5 , video encoder 500receives source video blocks and outputs a bitstream.

In the example illustrated in FIG. 5 , video encoder 500 may generateresidual data by subtracting a predictive video block from a sourcevideo block. The selection of a predictive video block is described indetail below. Summer 502 represents a component configured to performthis subtraction operation. In one example, the subtraction of videoblocks occurs in the pixel domain. Transform coefficient generator 504applies a transform, such as a discrete cosine transform (DCT), adiscrete sine transform (DST), or a conceptually similar transform, tothe residual block or sub-divisions thereof (e.g., four 8×8 transformsmay be applied to a 16×16 array of residual values) to produce a set ofresidual transform coefficients. Transform coefficient generator 504 maybe configured to perform any and all combinations of the transformsincluded in the family of discrete trigonometric transforms, includingapproximations thereof. Transform coefficient generator 504 may outputtransform coefficients to coefficient quantization unit 506. Coefficientquantization unit 506 may be configured to perform quantization of thetransform coefficients. The quantization process may reduce the bitdepth associated with some or all of the coefficients. The degree ofquantization may alter the rate-distortion (i.e., bit-rate vs. qualityof video) of encoded video data. The degree of quantization may bemodified by adjusting a quantization parameter (QP). A quantizationparameter may be determined based on slice level values and/or CU levelvalues (e.g., CU delta QP values). QP data may include any data used todetermine a QP for quantizing a particular set of transformcoefficients. As illustrated in FIG. 5 , quantized transformcoefficients (which may be referred to as level values) are output toinverse quantization and transform coefficient processing unit 508.Inverse quantization and transform coefficient processing unit 508 maybe configured to apply an inverse quantization and an inversetransformation to generate reconstructed residual data. As illustratedin FIG. 5 , at summer 510, reconstructed residual data may be added to apredictive video block. In this manner, an encoded video block may bereconstructed and the resulting reconstructed video block may be used toevaluate the encoding quality for a given prediction, transformation,and/or quantization. Video encoder 500 may be configured to performmultiple coding passes (e.g., perform encoding while varying one or moreof a prediction, transformation parameters, and quantizationparameters). The rate-distortion of a bitstream or other systemparameters may be optimized based on evaluation of reconstructed videoblocks. Further, reconstructed video blocks may be stored and used asreference for predicting subsequent blocks.

Referring again to FIG. 5 , intra prediction processing unit 512 may beconfigured to select an intra prediction mode for a video block to becoded. Intra prediction processing unit 512 may be configured toevaluate a frame and determine an intra prediction mode to use to encodea current block. As described above, possible intra prediction modes mayinclude planar prediction modes, DC prediction modes, and angularprediction modes. Further, it should be noted that in some examples, aprediction mode for a chroma component may be inferred from a predictionmode for a luma prediction mode. Intra prediction processing unit 512may select an intra prediction mode after performing one or more codingpasses. Further, in one example, intra prediction processing unit 512may select a prediction mode based on a rate-distortion analysis. Asillustrated in FIG. 5 , intra prediction processing unit 512 outputsintra prediction data (e.g., syntax elements) to entropy encoding unit518 and transform coefficient generator 504. As described above, atransform performed on residual data may be mode dependent (e.g., asecondary transform matrix may be determined based on a predictionmode).

Referring again to FIG. 5 , inter prediction processing unit 514 may beconfigured to perform inter prediction coding for a current video block.Inter prediction processing unit 514 may be configured to receive sourcevideo blocks and calculate a motion vector for PUs of a video block. Amotion vector may indicate the displacement of a prediction unit of avideo block within a current video frame relative to a predictive blockwithin a reference frame. Inter prediction coding may use one or morereference pictures. Further, motion prediction may be uni-predictive(use one motion vector) or bi-predictive (use two motion vectors). Interprediction processing unit 514 may be configured to select a predictiveblock by calculating a pixel difference determined by, for example, sumof absolute difference (SAD), sum of square difference (SSD), or otherdifference metrics. As described above, a motion vector may bedetermined and specified according to motion vector prediction. Interprediction processing unit 514 may be configured to perform motionvector prediction, as described above. Inter prediction processing unit514 may be configured to generate a predictive block using the motionprediction data. For example, inter prediction processing unit 514 maylocate a predictive video block within a frame buffer (not shown in FIG.5 ). It should be noted that inter prediction processing unit 514 mayfurther be configured to apply one or more interpolation filters to areconstructed residual block to calculate sub-integer pixel values foruse in motion estimation. Inter prediction processing unit 514 mayoutput motion prediction data for a calculated motion vector to entropyencoding unit 518.

Referring again to FIG. 5 , filter unit 516 receives reconstructed videoblocks and coding parameters and outputs modified reconstructed videodata. Filter unit 516 may be configured to perform deblocking and/orSample Adaptive Offset (SAO) filtering. SAO filtering is a non-linearamplitude mapping that may be used to improve reconstruction by addingan offset to reconstructed video data. It should be noted that asillustrated in FIG. 5 , intra prediction processing unit 512 and interprediction processing unit 514 may receive modified reconstructed videoblock via filter unit 216. Entropy encoding unit 518 receives quantizedtransform coefficients and predictive syntax data (i.e., intraprediction data and motion prediction data). It should be noted that insome examples, coefficient quantization unit 506 may perform a scan of amatrix including quantized transform coefficients before thecoefficients are output to entropy encoding unit 518. In other examples,entropy encoding unit 518 may perform a scan. Entropy encoding unit 518may be configured to perform entropy encoding according to one or moreof the techniques described herein. In this manner, video encoder 500represents an example of a device configured to generate encoded videodata according to one or more techniques of this disclosure.

Referring again to FIG. 1 , data encapsulator 107 may receive encodedvideo data and generate a compliant bitstream, e.g., a sequence of NALunits according to a defined data structure. A device receiving acompliant bitstream can reproduce video data therefrom. Further, asdescribed above, sub-bitstream extraction may refer to a process where adevice receiving a compliant bitstream forms a new compliant bitstreamby discarding and/or modifying data in the received bitstream. It shouldbe noted that the term conforming bitstream may be used in place of theterm compliant bitstream. In one example, data encapsulator 107 may beconfigured to generate syntax according to one or more techniquesdescribed herein. It should be noted that data encapsulator 107 need notnecessary be located in the same physical device as video encoder 106.For example, functions described as being performed by video encoder 106and data encapsulator 107 may be distributed among devices illustratedin FIG. 4 .

As described above, the signaling of profile, tier, level information inJVET-R2001 may be less than ideal. In one example, according to thetechniques herein, general_constraint_info( ) may be repositioned withinprofile_tier_level( ) syntax structure in order to ensure that syntaxelement general_level_idc can be parsed in the SPS without parsing anyvariable length or conditionally present syntax elements. Table 8illustrates an example of a profile_tier_level( ) syntax structure whichmay be signaled and/or parsed according to the techniques herein. Withrespect to Table 8, the semantics may be based on the semantics providedabove.

TABLE 8 Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { if( profileTierPresentFlag ) {general_profile_idc u(7) general_tier_flag u(1) } general_level_idc u(8)if( profileTierPresentFlag ) { general_constraint_info( )ptl_num_sub_profiles u(8) for( i = 0; i < num_sub_profiles; i++ )general_sub_profile_idc[ i ]  u(32) } for( i = 0; i <maxNumSubLayersMinus1; i++ ) sublayer_level_present_flag[ i ] u(1)while( !byte_aligned( ) ) ptl_alignment_zero_bit  f(1) for( i = 0; i <maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

It should be noted that it may be quite common that VVC bitstreams arecreated without any of the constraint flags applied, i.e. with allconstraint flags set equal to 0. In one example, according to thetechniques herein, a profile_tier_level( ) syntax structure may includea syntax element indicating that the constraint flags are not signaled,i.e., that general_constraint_info( ) is not present in aprofile_tier_level( ). Table 9 illustrates an example of aprofile_tier_level( ) syntax structure which may be signal and/or parsedaccording to the techniques herein.

TABLE 9 Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { if( profileTierPresentFlag ) {general_profile_idc u(7) general_tier_flag u(1)general_constraint_present_flag u(1) if( general_constraint_present_flag) general_constraint_info( ) } general_level_idc u(8) if(profileTierPresentFlag ) { num_sub_profiles u(8) for( i = 0; i <num_sub_profiles; i++ ) general_sub_profile_idc[ i ]  u(32) } for( i =0; i < maxNumSubLayersMinus1; i++ ) sublayer_level_present_flag[ i ]u(1) while( !byte_aligned( ) ) ptl_alignment_zero_bit  f(1) for( i = 0;i < maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

With respect to Table 9, the semantics may be based on the semanticsprovided above with an inference rule for all flags so that the flagsare inferred to be equal to 0 when not present. For example, aninference rule expressed in a xxxx_constraint_flag syntax element asfollows: When not present, the value of xxxx_constraint_flag is inferredto be equal to 0. Further, the semantics for syntax elementgeneral_constraint_present_flag based on the following:

general_constraint_present_flag equal to 1 specifies thatgeneral_constraint_info( ) is present in the profile_tier_level( )syntax structure. general_constraint_present_flag equal to 0 specifiesthat general_constraint_info( ) is not present in theprofile_tier_level( ) syntax structure.

It should be noted that Table 8 may be modified to include:

general_constraint_present_flag u(1) if( general_constraint_present_flag)immediately preceding general_constraint_info( ).

More generally, general_constraint_present_flag may be used to conditionthe presence of general_constraint_info( ) in a profile_tier_level( )regardless of the position of general_constraint_info( ) withinprofile_tier_level( ). Further, general_constraint_present_flag does notnecessarily need to immediately precede general_constraint_info( ).

Further, in one example, according to the techniques herein, syntaxelement ptl_num_sub_profiles may be repositioned to be directlysubsequent to syntax element general_constraint_present_flag and changedto be represented by 7 bits, instead of 8, in order to keep the bytealignment (regardless of the value of the flag). Table 10 illustrates anexample of a profile_tier_level( ) syntax structure which may besignaled and/or parsed according to the techniques herein. With respectto Table 10, the semantics may be based on the semantics provided above,with an inference rule for all flags so that the flags are inferred tobe equal to 0 when not present.

TABLE 10 Descriptor profile_tier_level( profileTierPresentFlag,maxNumSubLayersMinus1 ) { if( profileTierPresentFlag ) {general_profile_idc u(7) general_tier_flag u(1) } general_level_idc u(8)if( profileTierPresentFlag ) { general_constraint_present_flag u(1)ptl_num_sub_profiles u(7) if( general_constraint_present_flag )general_constraint_info( ) for( i = 0; i < num_sub_profiles; i++ )general_sub_profile_idc[ i ]  u(32) } for( i = 0; i <maxNumSubLayersMinus1; i++ ) sublayer_level_present_flag[ i ] u(1)while( !byte_aligned( ) ) ptl_alignment_zero_bit  f(1) for( i = 0; i <maxNumSubLayersMinus1; i++ ) if( sublayer_level_present_flag[ i ] )sublayer_level_idc[ i ] u(8) }

In another example, according to the techniques herein, aptl_reserved_zero_7 bits syntax element (7 bits reserved for use infuture versions of the specification) may be included inprofile_tier_level( ) syntax structure, for example, directly precedingsyntax element general_constraint_present_flag. That is, for example,added to the profile_tier_level( ) syntax structure illustrated in Table9. This ensures that byte alignment is maintained regardless of thevalue of general_constraint_present_flag.

In another example, according to the techniques herein,general_constraint_info( ) syntax structure may be repositioned withinprofile_tier_level( ) syntax structure to be located after sub-profilesyntax. That is, for example, referring to Table 6, immediately afterplt_num_sub_profiles syntax element in one example, or immediately afterthe for loop for general_sub_profile_idc[i] syntax elements.

In one example, according to the techniques herein, the ability to notsignal general_constraint_info( ) may be unified with the extensionsignaling of the general_constraint_info( ). That is, in one example,the gci_num_reserved_bytes may be replaced by a length field at thestart of the general_constraint_info( ) syntax structure. The lengthfiled indicating the total length of the constraint flags, including theones that might be added in future versions of the VVC specification.Table 11 illustrates an example of a general_constraint_info( ) syntaxstructure which may be signaled and/or parsed according to thetechniques herein. With respect to Table 11, a technical advantage isthat it is possible to signal fewer flags (fewer bytes) for thegeneral_constraint_info( ) syntax structure when one or more of theconstraint flags are set to 0.

TABLE 11 Descriptor general_constraint_info( ) { gci_num_constraint_bytes u(8)  if( gci_num_constraint_bytes > 0 )  {general_non_packed_constraint_flag u(1)general_frame_only_constraint_flag u(1)general_non_projected_constraint_flag u(1)general_one_picture_only_constraint_flag u(1)max_bitdepth_constraint_idc u(4)  }  if( gci_num_constraint_bytes > 1 ) { intra_only_constraint_flag u(1) max_chroma_format_constraint_idc u(2)single_layer_constraint_flag u(1) all_layers_independent_constraint_flagu(1) no_ref_pic_resampling_constraint_flag u(1)no_res_change_in_clvs_constraint_flag u(1)one_tile_per_pic_constraint_flag u(1)  }  if( gci_num_constraint_bytes >2 )  { pic_header_in_slice_header_constraint_flag u(1)one_slice_per_pic_constraint_flag u(1)one_subpic_per_pic_constraint_flag u(1)no_qtbtt_dual_tree_intra_constraint_flag u(1)no_partition_constraints_override_constraint_flag u(1)no_sao_constraint_flag u(1) no_alf_constraint_flag u(1)no_ccalf_constraint_flag u(1)  }  if( gci_num_constraint_bytes > 3 )  {no_joint_cbcr_constraint_flag u(1) no_mrl_constraint_flag u(1)no_isp_constraint_flag u(1) no_mip_constraint_flag u(1)no_ref_wraparound_constraint_flag u(1) no_temporal_mvp_constraint_flagu(1) no_sbtmvp_constraint_flag u(1) no_amvr_constraint_flag u(1)  }  if(gci_num_constraint_bytes > 4 )  { no_bdof_constraint_flag u(1)no_dmvr_constraint_flag u(1) no_cclm_constraint_flag u(1)no_mts_constraint_flag u(1) no_sbt_constraint_flag u(1)no_lfnst_constraint_flag u(1) no_affine_motion_constraint_flag u(1)no_mmvd_constraint_flag u(1)  }  if( gci_num_constraint_bytes > 5 )  {no_smvd_constraint_flag u(1) no_prof_constraint_flag u(1)no_bcw_constraint_flag u(1) no_ibc_constraint_flag u(1)no_ciip_constraint_flag u(1) no_mmvd_constraint_flag u(1)no_gpm_constraint_flag u(1) no_ladf_constraint_flag u(1)  }  if(gci_num_constraint_bytes > 6 )  { no_transform_skip_constraint_flag u(1)no_bdpcm_constraint_flag u(1) no_palette_constraint_flag u(1)no_act_constraint_flag u(1) no_lmcs_constraint_flag u(1)no_cu_qp_delta_constraint_flag u(1) no_chroma_qp_offset_constraint_flagu(1) no_dep_quant_constraint_flag u(1)  }  if(gci_num_constraint_bytes > 7 )  { no_sign_data_hiding_constraint_flagu(1) no_tsrc_constraint_flag u(1)no_mixed_nalu_types_in_pic_constraint_flag u(1) no_trail_constraint_flagu(1) no_stsa_constraint_flag u(1) no_rasl_constraint_flag u(1)no_radl_constraint_flag u(1) no_idr_constraint_flag u(1)  }  if(gci_num_constraint_bytes > 8 )  { no_cra_constraint_flag u(1)no_gdr_constraint_flag u(1) no_aps_constraint_flag u(1)gci_reserved_zero_5bits u(5)  }  for( i = 0; i <gci_num_constraint_bytes − 9; i++ ) gci_reserved_byte[ i ] u(8) }

With respect to Table 11, the semantics may be based on the semanticsprovided above with an inference rule for all flags so that the flagsare inferred to be equal to 0 when not present and the semantics forsyntax element gci_num_constraint_bytes based on the following:

gci_num_constraint_bytes specifies the length in bytes of the generalconstraint info structure, not including the byte used for signallinggci_num_constraint_bytes itself. The value of gci_num_constraint_bytesshall be in the range of 0 to 9, inclusive. Other values ofgci_num_constraint_bytes are reserved for future use by ITU-T|ISO/IECand shall not be present in bitstreams conforming to this version ofthis Specification.

In one example, according to the techniques herein, it may be beneficialto constrain the options provided to encoders so that either noconstraint information is sent (zero bytes) or all defined constraintinfo is sent (i.e., e.g., 9 bytes of constraint information is includedin general constraint information). Table 12 illustrates an example of ageneral_constraint_info( ) syntax structure which may be signaled and/orparsed according to the techniques herein.

TABLE 12 Descriptor general_constraint_info( ) { gci_num_constraint_bytes u(8)  if( gci_num_constraint_bytes > 8 )  {general_non_packed_constraint_flag u(1)general_frame_only_constraint_flag u(1)general_non_projected_constraint_flag u(1)general_one_picture_only_constraint_flag u(1)max_bitdepth_constraint_idc u(4) intra_only_constraint_flag u(1)max_chroma_format_constraint_idc u(2) single_layer_constraint_flag u(1)all_layers_independent_constraint_flag u(1)no_ref_pic_resampling_constraint_flag u(1)no_res_change_in_clvs_constraint_flag u(1)one_tile_per_pic_constraint_flag u(1)pic_header_in_slice_header_constraint_flag u(1)one_slice_per_pic_constraint_flag u(1)one_subpic_per_pic_constraint_flag u(1)no_qtbtt_dual_tree_intra_constraint_flag u(1)no_partition_constraints_override_constraint_flag u(1)no_sao_constraint_flag u(1) no_alf_constraint_flag u(1)no_ccalf_constraint_flag u(1) no_joint_cbcr_constraint_flag u(1)no_mrl_constraint_flag u(1) no_isp_constraint_flag u(1)no_mip_constraint_flag u(1) no_ref_wraparound_constraint_flag u(1)no_temporal_mvp_constraint_flag u(1) no_sbtmvp_constraint_flag u(1)no_amvr_constraint_flag u(1) no_bdof_constraint_flag u(1)no_dmvr_constraint_flag u(1) no_cclm_constraint_flag u(1)no_mts_constraint_flag u(1) no_sbt_constraint_flag u(1)no_lfnst_constraint_flag u(1) no_affine_motion_constraint_flag u(1)no_mmvd_constraint_flag u(1) no_smvd_constraint_flag u(1)no_prof_constraint_flag u(1) no_bcw_constraint_flag u(1)no_ibc_constraint_flag u(1) no_ciip_constraint_flag u(1)no_mmvd_constraint_flag u(1) no_gpm_constraint_flag u(1)no_ladf_constraint_flag u(1) no_transform_skip_constraint_flag u(1)no_bdpcm_constraint_flag u(1) no_palette_constraint_flag u(1)no_act_constraint_flag u(1) no_lmcs_constraint_flag u(1)no_cu_qp_delta_constraint_flag u(1) no_chroma_qp_offset_constraint_flagu(1) no_dep_quant_constraint_flag u(1)no_sign_data_hiding_constraint_flag u(1) no_tsrc_constraint_flag u(1)no_mixed_nalu_types_in_pic_constraint_flag u(1) no_trail_constraint_flagu(1) no_stsa_constraint_flag u(1) no_rasl_constraint_flag u(1)no_radl_constraint_flag u(1) no_idr_constraint_flag u(1)no_cra_constraint_flag u(1) no_gdr_constraint_flag u(1)no_aps_constraint_flag u(1) gci_reserved_bits u(5)  }  for( i = 0; i <gci_num_constraint_bytes − 9; i++ ) gci_reserved_byte[ i ] u(8) }

With respect to Table 12, the semantics may be based on the semanticsprovided above with an inference rule for all flags so that the flagsare inferred to be equal to 0 when not present and with the semanticsfor syntax element gci_num_constraint_bytes based on the following:

gci_num_constraint_bytes specifies the length in bytes of the generalconstraint info structure, not including the byte used for signallinggci_num_constraint_bytes itself. The value of gci_num_constraint_bytesshall be equal to 0 or equal to 9. Other values ofgci_num_constraint_bytes are reserved for future use by ITU-T|ISO/IECand shall not be present in bitstreams conforming to this version ofthis Specification.

It should be noted that the example general_constraint_info( ) syntaxstructures provided in Table 11 and Table 12 may be used in combinationwith any of the profile_tier_level( ) syntax structures described above.

In this manner, source device 102 represents an example of a deviceconfigured to signal a syntax element in a profile tier level syntaxstructure specifying whether a general constraint information syntaxstructure is present in the profile tier level syntax structure, andconditionally signal a general constraint information syntax structurein the profile tier level syntax structure based on the value of thesyntax element.

Referring again to FIG. 1 , interface 108 may include any deviceconfigured to receive data generated by data encapsulator 107 andtransmit and/or store the data to a communications medium. Interface 108may include a network interface card, such as an Ethernet card, and mayinclude an optical transceiver, a radio frequency transceiver, or anyother type of device that can send and/or receive information. Further,interface 108 may include a computer system interface that may enable afile to be stored on a storage device. For example, interface 108 mayinclude a chipset supporting Peripheral Component Interconnect (PCI) andPeripheral Component Interconnect Express (PCIe) bus protocols,proprietary bus protocols, Universal Serial Bus (USB) protocols, I²C, orany other logical and physical structure that may be used tointerconnect peer devices.

Referring again to FIG. 1 , destination device 120 includes interface122, data decapsulator 123, video decoder 124, and display 126.Interface 122 may include any device configured to receive data from acommunications medium. Interface 122 may include a network interfacecard, such as an Ethernet card, and may include an optical transceiver,a radio frequency transceiver, or any other type of device that canreceive and/or send information. Further, interface 122 may include acomputer system interface enabling a compliant video bitstream to beretrieved from a storage device. For example, interface 122 may includea chipset supporting PCI and PCIe bus protocols, proprietary busprotocols, USB protocols, I²C, or any other logical and physicalstructure that may be used to interconnect peer devices. Datadecapsulator 123 may be configured to receive and parse any of theexample syntax structures described herein.

Video decoder 124 may include any device configured to receive abitstream (e.g., a sub-bitstream extraction) and/or acceptablevariations thereof and reproduce video data therefrom. Display 126 mayinclude any device configured to display video data. Display 126 maycomprise one of a variety of display devices such as a liquid crystaldisplay (LCD), a plasma display, an organic light emitting diode (OLED)display, or another type of display. Display 126 may include a HighDefinition display or an Ultra High Definition display. It should benoted that although in the example illustrated in FIG. 1 , video decoder124 is described as outputting data to display 126, video decoder 124may be configured to output video data to various types of devicesand/or sub-components thereof. For example, video decoder 124 may beconfigured to output video data to any communication medium, asdescribed herein.

FIG. 6 is a block diagram illustrating an example of a video decoderthat may be configured to decode video data according to one or moretechniques of this disclosure (e.g., the decoding process forreference-picture list construction described above). In one example,video decoder 600 may be configured to decode transform data andreconstruct residual data from transform coefficients based on decodedtransform data. Video decoder 600 may be configured to perform intraprediction decoding and inter prediction decoding and, as such, may bereferred to as a hybrid decoder. Video decoder 600 may be configured toparse any combination of the syntax elements described above in Tables1-12. Video decoder 600 may decode a picture based on or according tothe processes described above, and further based on parsed values inTables 1-12.

In the example illustrated in FIG. 6 , video decoder 600 includes anentropy decoding unit 602, inverse quantization unit and transformcoefficient processing unit 604, intra prediction processing unit 606,inter prediction processing unit 608, summer 610, post filter unit 612,and reference buffer 614. Video decoder 600 may be configured to decodevideo data in a manner consistent with a video coding system. It shouldbe noted that although example video decoder 600 is illustrated ashaving distinct functional blocks, such an illustration is fordescriptive purposes and does not limit video decoder 600 and/orsub-components thereof to a particular hardware or softwarearchitecture. Functions of video decoder 600 may be realized using anycombination of hardware, firmware, and/or software implementations.

As illustrated in FIG. 6 , entropy decoding unit 602 receives an entropyencoded bitstream. Entropy decoding unit 602 may be configured to decodesyntax elements and quantized coefficients from the bitstream accordingto a process reciprocal to an entropy encoding process. Entropy decodingunit 602 may be configured to perform entropy decoding according any ofthe entropy coding techniques described above. Entropy decoding unit 602may determine values for syntax elements in an encoded bitstream in amanner consistent with a video coding standard. As illustrated in FIG. 6, entropy decoding unit 602 may determine a quantization parameter,quantized coefficient values, transform data, and prediction data from abitstream. In the example, illustrated in FIG. 6 , inverse quantizationunit and transform coefficient processing unit 604 receives aquantization parameter, quantized coefficient values, transform data,and prediction data from entropy decoding unit 602 and outputsreconstructed residual data.

Referring again to FIG. 6 , reconstructed residual data may be providedto summer 610. Summer 610 may add reconstructed residual data to apredictive video block and generate reconstructed video data. Apredictive video block may be determined according to a predictive videotechnique (i.e., intra prediction and inter frame prediction). Intraprediction processing unit 606 may be configured to receive intraprediction syntax elements and retrieve a predictive video block fromreference buffer 614. Reference buffer 614 may include a memory deviceconfigured to store one or more frames of video data. Intra predictionsyntax elements may identify an intra prediction mode, such as the intraprediction modes described above. Inter prediction processing unit 608may receive inter prediction syntax elements and generate motion vectorsto identify a prediction block in one or more reference frames stored inreference buffer 616. Inter prediction processing unit 608 may producemotion compensated blocks, possibly performing interpolation based oninterpolation filters. Identifiers for interpolation filters to be usedfor motion estimation with sub-pixel precision may be included in thesyntax elements. Inter prediction processing unit 608 may useinterpolation filters to calculate interpolated values for sub-integerpixels of a reference block. Post filter unit 614 may be configured toperform filtering on reconstructed video data. For example, post filterunit 614 may be configured to perform deblocking and/or Sample AdaptiveOffset (SAO) filtering, e.g., based on parameters specified in abitstream. Further, it should be noted that in some examples, postfilter unit 614 may be configured to perform proprietary discretionaryfiltering (e.g., visual enhancements, such as, mosquito noisereduction). As illustrated in FIG. 6 , a reconstructed video block maybe output by video decoder 600. In this manner, video decoder 600represents an example of a device configured parse a syntax element in aprofile tier level syntax structure specifying whether a generalconstraint information syntax structure is present in the profile tierlevel syntax structure, and conditionally parse a general constraintinformation syntax structure in the profile tier level syntax structurebased on the value of the syntax element.

In one or more examples, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored on or transmitted over as oneor more instructions or code on a computer-readable medium and executedby a hardware-based processing unit. Computer-readable media may includecomputer-readable storage media, which corresponds to a tangible mediumsuch as data storage media, or communication media including any mediumthat facilitates transfer of a computer program from one place toanother, e.g., according to a communication protocol. In this manner,computer-readable media generally may correspond to (1) tangiblecomputer-readable storage media which is non-transitory or (2) acommunication medium such as a signal or carrier wave. Data storagemedia may be any available media that can be accessed by one or morecomputers or one or more processors to retrieve instructions, codeand/or data structures for implementation of the techniques described inthis disclosure. A computer program product may include acomputer-readable medium.

By way of example, and not limitation, such computer-readable storagemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage, or other magnetic storage devices, flashmemory, or any other medium that can be used to store desired programcode in the form of instructions or data structures and that can beaccessed by a computer. Also, any connection is properly termed acomputer-readable medium. For example, if instructions are transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, digital subscriber line (DSL), orwireless technologies such as infrared, radio, and microwave, then thecoaxial cable, fiber optic cable, twisted pair, DSL, or wirelesstechnologies such as infrared, radio, and microwave are included in thedefinition of medium. It should be understood, however, thatcomputer-readable storage media and data storage media do not includeconnections, carrier waves, signals, or other transitory media, but areinstead directed to non-transitory, tangible storage media. Disk anddisc, as used herein, includes compact disc (CD), laser disc, opticaldisc, digital versatile disc (DVD), floppy disk and Blu-ray disc wheredisks usually reproduce data magnetically, while discs reproduce dataoptically with lasers. Combinations of the above should also be includedwithin the scope of computer-readable media.

Instructions may be executed by one or more processors, such as one ormore digital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules configured for encoding anddecoding, or incorporated in a combined codec. Also, the techniquescould be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a wide varietyof devices or apparatuses, including a wireless handset, an integratedcircuit (IC) or a set of ICs (e.g., a chip set). Various components,modules, or units are described in this disclosure to emphasizefunctional aspects of devices configured to perform the disclosedtechniques, but do not necessarily require realization by differenthardware units. Rather, as described above, various units may becombined in a codec hardware unit or provided by a collection ofinteroperative hardware units, including one or more processors asdescribed above, in conjunction with suitable software and/or firmware.

Moreover, each functional block or various features of the base stationdevice and the terminal device used in each of the aforementionedembodiments may be implemented or executed by a circuitry, which istypically an integrated circuit or a plurality of integrated circuits.The circuitry designed to execute the functions described in the presentspecification may comprise a general-purpose processor, a digital signalprocessor (DSP), an application specific or general applicationintegrated circuit (ASIC), a field programmable gate array (FPGA), orother programmable logic devices, discrete gates or transistor logic, ora discrete hardware component, or a combination thereof. Thegeneral-purpose processor may be a microprocessor, or alternatively, theprocessor may be a conventional processor, a controller, amicrocontroller or a state machine. The general-purpose processor oreach circuit described above may be configured by a digital circuit ormay be configured by an analogue circuit. Further, when a technology ofmaking into an integrated circuit superseding integrated circuits at thepresent time appears due to advancement of a semiconductor technology,the integrated circuit by this technology is also able to be used.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A method of decoding video data, the methodcomprising: receiving a general constraints information syntax structureby using a present flag variable in a profile level tier syntaxstructure providing level information and general constraintsinformation; decoding a first syntax element specifying whether firstconstraint flags are present in the general constraints informationsyntax structure; decoding the first constraint flags in the generalconstraints information syntax structure; decoding a second syntaxelement specifying a length of additional flags in the generalconstraints information syntax structure; and decoding second constraintflags in the general constraints information syntax structure in a casethat (i) a value of the first syntax element is equal to a first valueand (ii) a value of the second syntax element is greater than a secondvalue, and otherwise not decoding the second constraint flags.
 2. Adevice for decoding coded data, the device comprising: a processor; anda memory associated with the processor, wherein the processor isconfigured to: receive a general constraints information syntaxstructure by using a present flag variable in a profile level tiersyntax structure providing level information and general constraintsinformation; decode a first syntax element specifying whether firstconstraint flags are present in the general constraints informationsyntax structure; decode the first constraint flags in the generalconstraints information syntax structure; decode a second syntax elementspecifying a length of additional flags in the general constraintsinformation syntax structure; and decode second constraint flags in thegeneral constraints information syntax structure in a case that (i) avalue of the first syntax element is equal to a first value and (ii) avalue of the second syntax element is greater than a second value, andotherwise not decode the second constraint flags.
 3. A device forencoding image data, the device comprising: a processor; and a memoryassociated with the processor, wherein the processor is configured to:signal a general constraints information syntax structure by using apresent flag variable in a profile level tier syntax structure providinglevel information and general constraints information, and the generalconstraints information syntax structure includes: (i) a first syntaxelement specifying whether first constraint flags are present in thegeneral constraints information syntax structure; (ii) the firstconstraint flags in the general constraints information syntaxstructure; (iii) a second syntax element specifying a length ofadditional flags in the general constraints information syntaxstructure; and (iv) second constraint flags in the general constraintsinformation syntax structure in a case that (i) a value of the firstsyntax element is equal to a first value and (ii) a value of the secondsyntax element is greater than a second value, and otherwise notincludes the second constraint flags.